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Problems /Solutions with Blowflies in nests (Part 2)In addition to Messages that have appeared in the Bluebird Mailing Lists on this topic, the following are on the Audubon Society of Omaha website: Terry Whitworth's Blowfly web siteDate: Tue, 20 Mar 2001 12:13:09 EST Just a note regarding the discussion of whether I still want old bird nests. I will continue to examine all nests sent to me. For you veterans who have sent me many bluebird nests, it is not necessary unless you get something unusual. I still need bluebird nests from the Midwest, especially Iowa, Missouri, Nebraska and states to the South and west of these areas. I also will be happy to examine any nests if they want to know if their nests are infested. Barry Whitney is preparing a website for me that should help if you want to learn more about bird blowflies. I will let you know when it is ready, which should be any day now. I need more chickadee and wren nests and any other small cavity nesters. I also need nests of warblers, flycatchers, small sparrows, barn and bank swallows, and large birds like crows, hawks and owls. For all the nests sent from the eastern US, I still have not found several species of bird blowflies known to occur in the area. I'm not complaining, your contributions have generated enough data to keep busy for several years. Terry Whitworth Date: Wed, 21 Mar 2001 11:09:59 EST Bluebirders, My bird blowfly website is now up and running, thanks to Barry Whitney. The address is http://www.birdblowfly.com .We've tried to put a lot of information on this site and have lots of pictures. There is also a form for those of you sending nests. Please let us know what you think. Terry Whitworth Date: Wed, 16 May 2001 12:26:09 EDT Hello All, Today I cleaned out my backyard nestbox that fledged 5 bluebirds yesterday. I
saw one actually fledge and spotted two others nearby, never saw the other two.
This was the first nest that the bluebirds used grasses and rootlets instead of
pine needles in my backyard in 18 years. I always tear apart and inspect
carefully the used nests and have never found any evidence of blowflies. Much to
my surprise I found 15-20 blowfly larva and a couple of pupae. From all I've read and learned, the first nesting of the season usually
doesn't have this problem and it has been extremely dry since early April. We
did have two hot spells of 90+ degrees and was wondering if that, plus the
different nesting material used was the difference in the blowfly infestation. I
never saw any when checking the nest during the cycle and when I tore the nest
apart they were clustered together in the very center of the nest below the nest
cup. I feel bad that I didn't check more carefully during the nesting cycle
and hope the fledglings were not weakened by this. I'll be watching for evidence
that they survived in the coming weeks as I expect this pair to renest and bring
the fledglings around. Date: Wed, 16 May 2001 14:49:55 -0400 (EDT) Hello Laura and all, Since all nestlings fledged they must have been up to strength. Finding blow fly larva in a nest is normal and usually isn't any problem. The larva were not advanced enough to become a fatal problem. You didn't mention sending in this nest as part of the study by Terry Whitworth. This is the kind he needs. Keep an eye on the later nestlings as they grow. Joe Huber Venice Fl. Charter member NABS, Charter member OBS, Life member OBS Joe Huber... Date: Wed, 16 May 2001 13:52:09 -0700 Dear Laura and friends, Sorry about the infestation. Not during the nesting season, but when all the nesting action is behind us, powder the inside of the nesting box with a little sulfur dust. This should help combat Blowflies and other insect infestations for next years fun. You bring up an important point having "two hot spells of 90+ degrees" and Blowflies. I have been wanting to explore for along time the use of Beneficial Nematodes in dealing with these and other insect pests. I don't want to stick my neck out to far on this one, but hear me out. Beneficial Nematodes are a great way to biologically deal with insect pupae or larva. They attack the pupae or larva in a similar fashion as the Blowfly larva attacks the Bluebirds. The only difference is the the Beneficial Nematodes completely devour the pupae or larva. Beneficial Nematodes are applied to the ground to eat up the dormant pupae or larva before they hatch in the spring, which reducing the insect population. The Bluebirds, Tree and Barn Swallows deal with the ones that hatched and escaped the Beneficial Nematodes. Beneficial Nematodes are completely harmless to humans, pets and possibly even our feathered friends. I haven't had Blowflies ever, but I have only been Bluebirding for 5 years in our vineyards and not "18 years" like you. However, this is one of those things that make you want to say, "Hum?" Please, I'm not recommending that everybody go out there and start tossing Beneficial Nematodes into their nesting boxes far from it. Perhaps an application around the yard would be enough and let me reiterate they are completely safe. Give me a chance to talk with some of my local agricultural buddies or
friends at UC Davis before taking any action. If anyone is interested in having
me dig Regards to all, ... Date: Wed, 16 May 2001 18:50:03 -0400 Hi John and all, I for one would be very interested in any further information on beneficial nematodes. I assume they would prey on larvae of all kinds, not just blowflies, and would like to see any information that shows whether or not birds can safely eat larvae from lawns treated with these nematodes. I would hate to inadvertently poison insect-eating creatures like bluebirds. Might not some larvae be contaminated but not destroyed? What happens when and if birds then eat such contaminated "dinners"? I would also be interested in how climate affects success rates for your nematodes. One example that comes to mind is the milky spore put down on lawns to kill larvae of Japanese beetles, which unfortunately does not work well here in the far north (Lake Ontario snowbelt north of Syracuse NY). Dot Date: Fri, 18 May 2001 06:47:26 -0700 (PDT) Yesterday afternoon I went to check on my 5, 12 day-old bluebirds (they aren't ready to fledge yet, so no worries there) and the whole bottom of the box was infested with beetles! I took all the young out and place them in a shoe box lined and covered with a towel and put them inside my house to stay warm. In the meantime, my husband and I cleaned out the box and tossed the old nesting material. I read on NABS web page that you are suppose to replace the original nest with dried grass in the same shape, but I only had a hand full of dried grass. Instead, I used shredded paper on the bottom and then put the grass I had on top of that. When I put the young back in they all kind of ended up one on top of the
other rather than in the neat little spiral they were in. I tried to adjust them
but it Did I do everything alright or have I messed up bluebirdville? Does anyone know if the beetles will return? Also, there was quite a bit of fecal matter all over the inside of the walls of their house. Being a first time bluebird host I'm not sure if this is normal. While the nestling were out, I scrubbed the inside walls with a dry brush and dusted out any loose matter. Any advice on any or all of the above would be much appreiciated. Thanks. Laura Date: Fri, 18 May 2001 10:56:28 -0400 (EDT) Hi Laura, You did ok by replacing the nest. As long as the babies are not injured by course nesting material it should be fine. I have replaced a Bluebird nest with parts of a Sparrow nest and it turned out fine. The parents are feeding them so they accepted the new nest. Hope you know the fledge day for them so you can witness their fledge. then you will know how good a job you did with nest building. Joe Huber venice, Fl. Charter member NABS, Charter member OBS, Life member OBS Joe Huber... Date: Sat, 19 May 2001 16:17:49 EDT I for one would be very interested in any further information on beneficial nematodes. I assume they would prey on larvae of all kinds, not just blowflies, and would like to see any information that shows whether or not birds can safely eat larvae from lawns treated with these nematodes. I would hate to inadvertently poison insect-eating creatures like bluebirds. Might not some larvae be contaminated but not destroyed? What happens when and if birds then eat such contaminated "dinners"? I'll see if I can find (someone with Internet access may be considerably quicker than I) a website for Arbico--that's the company from which I get my fly predator wasps, and I know they also sell nematodes, etc. But are the nematodes poisonous?? I always assumed it was the idea of the "fleas with littler fleas" or words to that effect! In any case, though I didn't more than glance at the nematode info in the catalog, I got the impression that the whole idea of what Arbico and similar companies sell, is to use control methods which are clean and safe for humans, birds, pets, etc. Rhonda Watts Date: Sat, 19 May 2001 21:23:41 -0400 Hi Rhonda and all interested, the main site is easy to find: www.arbico.com and I just visited it and found lots of stuff... Fawzi ... Date: Mon, 21 May 2001 09:45:50 EDT Bluebirders, Terry Whitworth Date: Fri, 25 May 2001 12:42:34 EDT How common are blow flies in the blue bird nests? I have a gilbertson with 5 babies in it, they are about a week old. I am wondering how one removes all the birds to check out the nest for blow flies without distressing the parents quite a bit. Since it is raining so much here, what other than grass, can be used to preplace the nesting material? Thanks, Date: Fri, 25 May 2001 13:27:45 -0400 Sandy's dilemma might be mine as well (someday) and it just gave me an idea. Terry ("the bug collector") doesn't need the used bluebird nests near as much as the other types of nests ... and oneday I might just need a "replacement nest" that I can't replace easily or near as adeptly as the bluebirds. When I get a "used" nest ... I'll put it aside for an "emergency". Question: Is there any safe and effective way to rid the used nest of parasites / larvae, other harmful teeny things? I know parasites themselves can't live without a host but ... What about the other things that crawl, creep, bite, etc.??? Thanks for all the great questions everyone.... and many many thanks for all the incredibly helpful and insightful discussions! Sincerely, Date: Fri, 25 May 2001 14:36:54 EDT There have been a couple questions about how to deal with nest parasites. See my website for a discussion of this issue and pictures of heavily infested birds. I have a photo of a nestling magpie with feeding spots from blowfly larvae. These are actually just scabs. You can examine the naked abdomen of nestlings and if you see these spots you know they are heavily infested. I consider parasites, including fleas, mites and blowflies natural and I would do nothing unless the problem is severe. Nest substitution seems to be the most common practice to deal with a severe infestation. Terry Whitworth Date: Fri, 25 May 2001 14:38:55 -0400 Guys: Do not use old nests as replacement nests! Always build replacement nests using dry grass clippings, dry pine straw, etc. Make a nice, comfortable bowl like nest similar to the size of the original. The parents will will be too busy feeding their young to be concerned about the nest being perfect. But do your best. Being so cool, you may not have the problem with blowflies as some nests will later on. And to answer Samboy's question, the parents will get over it. Just place the babies in a shoebox with the top punched with a couple of air holes that has some dry grass clippings or pine needles in the bottom. Do your nest replacement and put the babies back, and mom and pop will resume feeding immediately. Work fairly fast, and good planning would be to have the replacement nest done ahead of time. If you don't have dry materials to work with, bring in the wet and dry them in a oven. You shouldn't be using green grass or green pine needles, though. Always dry grass clippings and pine straw which is dry pine needles. Robert ... Date: Fri, 25 May 2001 14:08:10 -0500 Robert--- Why not use old nests as replacement nests?? I have a complete Eastern Bluebird nest that was abandoned before they laid eggs. I saved the nest in case I need a replacement sometime. Could you please explain why you feel old nests shouldn't be used? Jay Gilliam Date: Fri, 25 May 2001 15:37:16 -0400 Robert and others, On what day after hatching would you do this nest swap? and, would you do it only after you find blowfly or regardless? -Laura Date: Fri, 25 May 2001 15:59:59 -0400 Hi list: For the past several years, I have left a patch of my back yard grow to about 8 or 9 inches. Then I mow it, collect the large blades of grass and dry it on a hot, sunny sidewalk for several hours. Even though it stays green, it is dry and brittle. During the second nesting, each EABL nest is replaced. The first nesting is free of blowflys, but all of the second nestings have them. When the chicks are no older than 12 days, I just scoop the old nest with birds out and put in a small pail covered with a towel. The new nest then is placed in a clean nest box and one by one the chicks are replaced. The parents are back in minutes, each with a worm. One time, after the chicks fledged, the parents used my nest for the second nesting, after the female re-shaped it a little. D. H. Snook/Sondra R. Snook Date: Fri, 25 May 2001 16:15:29 -0400 A nest that young may not be a problem. But the reason is quite simple, parasites. Robert Date: Fri, 25 May 2001 16:17:35 -0400 I would do nest replacements at around 10 days of age. On Puple Martins at 12 days of age. I only do one replacement unless there is evidence of severe parasite infestation. But that's just me. Robert ... Date: Fri, 25 May 2001 17:49:52 -0400 This issue of blowflies is almost as "complex" for me as the issue of HOSP control..... esp. with a philosophy that utilizes "choosing a path of least resistance"... is adhered to. At least I now know what to do for severe parasitic infestation *and* I have some dried grass waiting in the wings if a severe "emergency" arises. Will I use it at the first sign of blowfly infestation? Will I use it as a prevention measure? I honestly don't know yet, but I've learned (thanks to Terry's site) that in Pa., (and Ohio) blowfly infestations seem to be at their worst. If I do ... I hope I'll do at least 1/2 as good a job on the replacement as the Snooks apparently did!!! gr Susan / Freeburg, PA Date: Mon, 18 Jun 2001 13:33:23 EDT Shawna B. NW NJ Zone6 Hello All, I am trying to locate the article written by Terry Whitworth last year regarding his findings on Blowfly larva and the effects on the nestlings, he had posted it last year, here on the list and I am not sure how to find it, Any help locating it will be greatly appreciated, Thanks in advance Shawna Date: Mon, 18 Jun 2001 13:52:57 -0400 Hi Shawna, I believe you can probably find what you're looking for on Terry's web page. Here's the link: MJ ... Date: Mon, 18 Jun 2001 12:44:00 -0500 I think this bears repeating since someone requested it. Visit Terry's web site at http://www.birdblowfly.com KK ----- Original Message ----- After seeing the discussion on the list about bird blowflies, I'd like to make a few comments. The purpose of my study is to gather information on bird blowflies species,
distribution, infestation rates and nest populations. Bird disturbance is
minimal because I only look at nests after young fledge. Much of my past work on
bird blowflies has focused on the effect of blowfly larvae feeding on 1) Do bird blowflies harm nestlings? This means a nest with 4 nestlings would have to have 40 or more larvae in their nests. In many areas, this would be an unusual condition. In some areas of Ohio and Pennsylvania, last year it was common. If you would like a copy of a paper I published on this subject e-mail me with your address. 2) Should I check my nests for blowflies? If you suspect blowfly populations may be high in your area, inspect nestling abdomens for tiny scabs left by feeding larvae. In heavy infestations you also may observe larvae attached to nestlings. If you find heavily infested nests, you can physically remove larvae or do nest replacement as others have suggested. If you want help evaluating your nests for blowflies, wait until nestlings fledge and send me your nests. I will tell you if they are infested and what the numbers are. 3) Is there any reason not to control bird blowflies in nests? This is not the final word on these issues, feel free to comment further. Thanks to all that have sent me nests. Terry Whitworth, PhD From: "Bonnie A. Yeager"
dement"at"frognet.net We use fly repellent horse collars on our Horse farm. These horse collars look like a man's belt and are made of plastic (perforated) with a cork interlayer. The cork interlayer is impregnated with a mixture of oil of citronella (~75%) and oil of cedar (~25%). The manufacturer claims the collar will repel biting flies for up to two months. Next year, I am planning on attaching a 2-3 inch section from a horse collar inside of a nest box and above the entrance hole to act as a blowfly repellant. The entrance hole is the only way for blowflies to enter the box - all of the ventilation and drainage holes are covered with 1/8" hardware cloth. I was wondering if anyone has tried using oil of citronella and/or oil of
cedar as blowfly repellent(s) in a similar experiment? From: BBBMV"at"aol.com I hope it works. I tried garlic in nest boxes to repell sparrows. They just picked it up and dropped it out the hole, I found every one right under the box, and a sparrow nest inside! Bill Davis, Florida From: "Pamela Ford" jpford"at"home.com I have no idea if it has the same effect on birds, but oil of cedar can be quite harmful in small mammals - even to the point of causing pneumonia. Veterinarians now recommend that you don't use cedar chips for bedding for guinea pigs, etc. From: "Bonnie A. Yeager"
dement"at"frognet.net Some Fly Facts gleaned from various commercial pest control sites on the web: To take advantage of these behavioral characteristics to, hopefully, reduce blowfly infestation next year, I was thinking of putting fly paper around the top rim of a 4" PVC nest box and replacing its opaque PVC cap with a translucent one. The game plan is that flies, attracted by the odor of the nest will fly into the entrance hole, then up toward the translucent cap and get trapped on the fly paper. There is no other ways into the box except via the entrance hole. Of course, the location of the fly paper in the box is inaccessible to the birds. Please let me know what you think, pro or con, or if this type of experiment
has already been done. I don't want to reinvent the wheel!=20 Date: Tue, 15 Jan 2002 22:25:39 -0000 For those of you who may be bothered with Blowflies in the nest this summer, this suggestion might help. We haven't done this before, because we have not had this problem, but this year my husband is putting wire bottoms in all the houses and a false wood floor that can be removed after the nest is built. This should eliminate the Blowfly problem. I hope it does.Anything to help the Bluebirds survive. Jeanette in MS. Date: Wed, 06 Mar 2002 11:47:47 -0800 As you will see, Terry Whitworth is still interested in receiving nests but
mostly of other species besides bluebirds and Tree Swallows. Tue, 26 Feb 2002 17:40:48 -0500 (EST) Hatch, Terry Whitworth From: "BONNIE A. YEAGER" dement"at"frognet.net
The boxes are described as follows: 1. PVC T design. The bottom of the nest is protected with a screen covered
PVC cap - control. So far this year only one PVC box is occupied by bluebirds (Box 2). It appears as though my experiments are for the BIRDS in 2002! Box 2 was successful in fledging 8 bluebirds last year and Box 4 was successful in fledging 4 Chickadees. Oh well, It looks like I will have to wait until 2003 to get any data, but it may be too early to throw in the towel. This year the first bluebird egg was observed on 4/13/02 in Box 2. A total of 4 eggs were laid on consecutive days and the female commenced incubation on 4/16/02. Last year the first bluebird egg was observed on 4/10/02, so everything in SE OH appears on schedule even though the winter was milder than usual. I will not check this box again until late next week, since the weather has been cold and I don't want to disturb Mom. No HOSP or other predator problems to report. ... For those of you with insect problems, Bounce (the fabric softener) is supposed to repel ants and bees. I haven't tried it, but I may try it next year to see what affect it has on blowflies. ... Fred Yeager, From: "Gary Springer" springer"at"alltel.net Until this year, I have never had a problem with blowfly larvae in nest boxes. Many sources I've read indicate that bluebird chicks in nests infested with these parasites normally do not die. Although my experience in this area is only beginning, it seems this parasite would pose a more serious threat to smaller birds such as tufted titmice and chickadees. Today I discovered 6 dead tufted titmouse chicks in a box that contained about 35 larvae. (It is possible some other factor caused these birds to die) I removed an average of 20 larvae from three other tufted titmice nests and checked several chickadee nests but no larvae were present in the chickadee nests. Another interesting observation I made while examining the tufted titmice nests is that there was more than an eighth cup of extremely fine dirt inside the nest boxes with the larvae. (this was dirt, not the fine material shed during formation of feathers) Since birds take dust baths for relief from mites, is it possible that the adult tufted titmice transferred this dust from its wings to the chicks inside the nest box in an effort to get relief form the blowfly larvae? Or, is it just that I didn't notice the accumulation of dirt inside tufted titmice nests? Gary Springer From: "John C James" jjames14"at"nc.rr.com Query: If birds that are fledged did have blowfly larvae on them when they left the nest, what consequences, if any, would they suffer as a result.? Would they themselves infect other birds of their species, or would they simply eliminate the larvae themselves, or with the aid of their parents?? John James From: "Karen Louise Lippy" brdbrain"at"superpa.net Gary, Many times, when chicks die in our boxes and I am told about it, I ask the monitors to check for signs of blowfly infestation. They always tell me they can't see any. If I go with them to the box, I always invariably find the hard casings formed by the larvae (in which they become the adult fly) lying in the bottom of the box. If the blowfly has been feeding on the chicks long enough to cause their deaths, this is the first place you should check for signs of infestation, in the bottom of the box and look for black oblong pellets which resemble rat turds (not a scientific, but appropriate description of the larval casings.) Karen from South Central PA ... From: "Keith & Sandy Kridler" kridler"at"1starnet.com Keith Kridler Mt. Pleasant, Texas I also believe that something different about the nest styles is attracting the blowflies to these nests when 50 feet away bluebird nests are not affected. I have always suspected the smelly animal fur or hair but she might be right about it being the green moss. The titmice and chickadees also have a lot more moisture from the moss in their nests and there is normally quite a bit of dirt that I believe is pulled up with the moss as the birds collect it. Blowflies are more like leaches and will stay in the nest/box and will not be carried on the adults or fledglings as they leave the nestbox for very long. High levels of parasites can make the young birds uncomfortable and on rare occasions will have them leave the nestbox early. Can someone post the link to Terry Whitworth's web page? I believe there are now about 9 species of blowflies known to infest "bluebird" nestboxes. Off to check boxes! KK From: "MJShearer" eshearer"at"attbi.com Hi Keith, Link to Terry Whitworth's blowfly site: http://members.aol.com/birdblowfly/index1.htm MJ From: hubertrap"at"webtv.net (Joe Huber) Hello Gary and all, It is my feeling that the fine dirt substance is droppings from the Blow fly larva. Blow fly larva comes from the adult Blow fly laying eggs in the nest then hatching out in the box. it only takes a few days for the larva to become large enough to attach to the young birds and suck blood. No one seems to know for sure why one best is bothered by them and others not. It has been determined how many larva it takes to be fatal in a nest, but I can't recall, Keith Kridler has this kind of info if you really want to know numbers. Best Wishes, Joe Huber Venice ,Fl. Charter member NABS, Charter member OBS, Life member OBS Joe Huber... From: hubertrap"at"webtv.net (Joe Huber) Hello John and all, If a young Bluebird flew from the nest with a blow fly larva attached would it effect the young bird? The larva will unattached after awhile and not fall back in bottom of nest so it may perish before becoming a fly. Don't think there could be enough larva on a fledging bird to cause serious problems. Blow fly is simply a adult Blow fly entering the nest box to lay eggs. The eggs hatch in a short time and the larva suck blood from the young birds in the nest. The more larva the more serious the harm to young birds. Timing of egg hatch to larva and bird hatch at proper time for larva feeding. Sometimes all things happen just right and birds suffer or die. If we catch them in time we can remove the contaminated nest and replace it with one we design. Birds will accept it if it holds young in place. By removing the old nest the larva are removed. It is a good idea to inspect young for attached larva and remove any you find. Joe Huber Venice Fl. ... From: "John C James" jjames14"at"nc.rr.com Query: If birds that are fledged did have blowfly larvae on them when they left the nest, what consequences, if any, would they suffer as a result.? Would they themselves infect other birds of their species, or would they simply eliminate the larvae themselves, or with the aid of their parents?? John James From: "MJShearer" eshearer"at"attbi.com Hi Gary, Maybe you should send that nest to Terry Whitworth for his evaluation. The unusually mild winter has resulted in a bumper crop of insects much earlier than we normally see them around here. (Atlanta) MJ This is from Terry's blowfly site: Bird Blowflies -------------------------------------------------------------------------------- Questions and Answers: 1) Do bird blowflies harm nestlings? This means a nest with 4 nestlings would have to have 40 or more larvae. In many areas, this would be an unusual condition. In some areas of Ohio and Pennsylvania, last year it was common. If you would like a copy of a paper I published on this subject e-mail me with your address. 2) Should I check my nests for blowflies while nestlings are in it? For the average birder, it's probably not necessary unless you have evidence of heavy infestations. Even in heavily infested nests, nestlings are rarely killed by blowfly larvae. Disturbing nestlings and parents by looking through their nest for larvae will cost birds energy, which may equal the energy used to replace blood lost to larvae. Also, you are disturbing some nests that are not infested. If you suspect blowfly populations may be high in your area, inspect nestling abdomens for tiny scabs left by feeding larvae. In heavy infestations you also may observe larvae attached to nestlings. If you find heavily infested nests, you can physically remove larvae or do nest replacement. If you want help evaluating your nests for blowflies, wait until nestlings fledge and send me your nests. I will tell you if they are infested and what the numbers are. It really helps to have a sheet of paper in the box with your name, address, and E-mail. If there is enough space on the sheet, I can write a rough draft response to you on your sheet and keep it on file in case I need to contact you. I then turn it over to my secretary who types a formal report. 3) Is there any reason not to control bird blowflies in nests? Bird blowflies, like mites, fleas, diseases, weather and other adversity allow survival of the fittest to function and helps ensure that only the fittest nestlings survive to reproduce. Nestlings which are protected from adversity may produce offspring that are less fit and less able to survive without human intervention. Remember bird blowflies are perfectly natural and have co-evolved with birds for millions of years. If they kill their hosts, they will die too. This is not the final word on these issues, feel free to comment further. Thanks to all who have sent me nests. -------------------------------------------------------------------------------- Nestling Bird Parasites (Find in page NESTLING BIRD PARASITES) Google search
information about the Bird Blowfly Go search information about the Bird Blowfly -------------------------------------------------------------------------------- Terry Whitworth, PhD Phone 253-531-7925 Email: WPCTWBUG"at"AOL.COM
... From: "Gary Springer" springer"at"alltel.net Regarding the recent loss of tufted titmice in a box containing about 35 blowfly larvae: I heard the live chicks inside the box 24 hours before I learned of their fate. There were 35 very active larvae about half inch long when extended as they crawled and nearly a quarter inch wide in the contracted position. There was a dark streak inside the larvae which appeared to be the blood of the chicks inside the digestive tract of the larvae. A significant portion of the approximately eighth cup of the debris I called dirt is primarily dry Georgia silt, which could not be associated with the feces of the larvae or the moss in the nest material which is normally collected from the sides of trees or decaying logs where this type of silt is not abundant. The weather was mild and food collection by the adults would have been very favorable The chicks were about two weeks old and were about a fourth the size of an adult bluebird. Twenty four hours after making the discovery(Discovery) of the dead titmice one clutch of bluebirds fledged from a box located 40 feet away from the box with the dead titmice. There wasn't a single blowfly larvae or pupae in the box that hosted the bluebirds. Within 48 hours of the discovery second clutch of bluebirds fledged from a
box located 60 yards from the dead titmice and a third clutch of bluebirds
fledged from a box 120 yards away. Again, not a single blowfly larvae or pupae
were in these two bluebird nests.(there is a fourth clutch of bluebirds is in
box about 200 yards away but it is too near fledge to In addition to the four boxes with bluebirds and the failed titmouse attempt noted above, there were 9 other nest boxes with nests located within about 200 yards of the box with the failed titmice attempt. All distances are approximate. 1) through 5) failed titmouse attempt and bluebirds as noted above 6) Carolina chickadees 50 yards away fledged 24 hours before Discovery-no larvae or pupae 7) Carolina chickadees 120 yards away fledged 48 hours before Discovery- 9 pupae 8) Carolina Chickadee 140 yards away box not yet checked as birds may fledge at any moment 9) Tufted titmouse 120 yards away 6 chicks approximately 13 days old 34 active larvae 10) Tufted titmouse 160 yards away 6 chicks about 12 days old 31 active larvae. 11) Carolina wren 100 yards away fledged about two weeks before Discovery-no pupae in nest 12) Carolina chickadee 170 yards away fledged 6 within 4 days of Discovery-19 pupae 13) Carolina Wren 140 yards away incubating-too early to notice blowfly infestation 14) Carolina Chickadee 145 yards away three day old chicks-probably too early to determine infestation Initial Suspicion: In the observation area, Tufted titmice and Carolina chickadees are more susceptible to blowfly infestation than bluebirds Note: This nest concentration occurred without any seed feeding after March 15(there were no extended periods of freezing temperatures during that period or feeding would have been resumed), and, there has never been a meal worm offered to birds on the property. Note: It is possible the blowfly infestation did not contribute to the demise of the tufted titmice. Gary Springer From: "Fread J" firefrost2"at"hotmail.com This may be "old hat" to many bluebirders, however, we have many new folks who this information could prove valuable and therefore I submit it: Visit Dr. Terry Whitworth's site on Bluebird Blowflies: http://www.bluebird.htmlplanet.com/blowflies.htm For taxonomic purposes, parasitic wasps (parasitica for short) are grouped together with bees, ants and other wasps into the insect order Hymenoptera. It is interesting to note that the Hymenoptera are one of the most species-rich group of insects in the world with several thousand species already described and doubtless thousands more to discover. In general, Hymenoptera have 2 pairs of wings (however some species are wingless) and they develop using complete metamorphosis (egg-larva-pupa-adult). Nearly all are carnivorous or insectivorous with the main exceptions being the Sawflies and Gall Wasps. A less obvious feature, but one that sets all Hymenoptera apart from most other insect groups, is a "haplo-diploid" genetic makeup! This means that only the females in any species have a full compliment of chromosomes--the males have half a set. Sex determination is done at the point of fertilization--fertilized eggs develop into females and unfertilized eggs develop into males. A tremendously powerful consequence of this process is that females can actually control the sex ratio of their offspring simply by controlling how many fertile (female) or infertile (male) eggs they lay. Technically speaking, "Parasitic Wasps" are not parasites--they are parasitoids. This is because a true parasite is something that lives at the expense of its host but doesn't actually kill it, whereas parasitoids nearly always kill their host. In general though most people still use the term "Parasitic Wasps". Parasitoid larvae usually develop by feeding on a single host--different species develop on anything from tiny aphids and insect eggs right up to large butterfly and moth larvae. They have evolved to live and feed inside the host's body cavity (endoparasitoids) or outside the host's body (ectoparasitoids). They can be solitary or gregarious--with anything from 1 to many 1000's of larvae consuming the same host. Nearly all parasitica inject venom into their host along with or just prior to the egg. This venom is a highly complex mixture of chemicals and other agents used not just to paralyze the host, but to also modify the host's tissues. Tissue modification is a feature of nearly all venoms, making the host more nutritious for the developing wasp larva and helping to overcome the host's immune systems. The latter is an especially important consideration for internal parasitoids as a host's body will usually try to surround (encapsulate) a foreign body to prevent infection and to kill any parasitoid egg or larvae. Parasitica have developed many ways of getting around this but I think the most diabolical and devious is the use of polydnaviruses! (Also known as Poly-DNA-viruses). These viruses are injected by some endoparasitoids with the venom and have been shown to target and disable the host's immune system totally---thus protecting the developing parasitoid. Other more basic methods of bypassing the host's immune system include laying the egg directly into the host's brain (ganglion), where the immune system is unable to encapsulate it! Whichever method the parasitoid uses to prevent encapsulation it must also protect itself against many other dangers. One of the most serious being the possibility that a host will succumb to a fungal or bacterial infection and die before the parasitoid has finished with it. Amazingly, many larvae secrete chemicals with antibiotic or antiseptic properties as they move around the host's body cavity. They also avoid damaging the host's gut (a massive source of bacteria) by eating non-essential areas first, like body fat and the reproductive organs. Many species also use teratocytes--bundles of cells that emerge from the egg with the embryo. These cells absorb food from he host's body cavity and the parasitoid larvae feeds on them--removing the need for it to feed directly on the host's tissues until it is absolutely necessary. One more fascinating trait and I will quit: Polyembryony is another complex strategy employed by parasitica but this time its aim is to ensure the maximum number of offspring from he fewest number of eggs! Some species lay a single egg that continues to divide, cloning itself into many independent larvae--in extreme examples one egg can produce thousands of larvae. Like some science fiction movie, some species have been shown to produce different types of larvae from the same egg--normal larvae that feed and develop fully into adult wasps and others, which never mature into adult wasps, that act as guards to protect the other from attack by other parasitoid larvae........ Fread J. Loane Date: Mon, 13 May 2002 10:11:42 -0700 (PDT) Gary Springer springer"at"alltel.net wrote: Initial Suspicion: In the observation area, Tufted titmice and Carolina chickadees are more susceptible to blowfly infestation than bluebirds Note: This nest concentration occurred without any seed feeding after March 15(there were no extended periods of freezing temperatures during that period or feeding would have been resumed), and, there has never been a meal worm offered to birds on the property. Note: It is possible the blowfly infestation did not contribute to the demise of the tufted titmice. Gary Springer Hello Gary, I agree with your conclusion concerning Blowfly infestation and nests made using moss. Nearly every CACH nest on my Indiana trail has had some degree of Blowfly infestation. The most severe infestation was 7 Blowfly per nestling; the nestlings did fine. Terry Whitworth's website indicates that 10 Blowfly per nestling wolud be a major problem for the chicks. I would guess that I have found Blowfly larvae in no more than 5% of my EABL and all of those infestations were observed in nests later in the nesting year, that is July through August. However, not all late season nests have the infestion. Out of 8 boxes (6 in IN & 2 in IL) that have have fledged EABL this year, no Blowfly have been observed. I have not inspected 3 CACH nests as of yet but will update you on my findings later. Have a good day Bob Sitarski a.k.a The Doctor, Jackson County Indiana ( 385244N 086023W ) & Clay County Illinois ( 384008N 0882908W ) Date: Fri, 05 Jul 2002 08:32:34 -0400 Haleya Priest Amherst MA But really we would be looking at 50 +/- to be alarmed!!!!!! I simply lift the nest - but I do it after they've all made their way back down to the bottom of the box to hide - after 11:00am or so - If you do it early in the morning you'll miss many of them as many are still in transport from the birds to the bottom of the nest. I lift up the nest, shake the nest gently and brush them out. I do this a couple few days in a row and it takes care of the problem. It also should be done when the babies are 7-10 days old - not before because they (the blowflies) really aren't developed enough and big enough to present much of a problem. These little larvae are really important food for a kind of wasp so these aren't our worst enemies! And they don't need to be sprayed! If all we ever had to worry about were blowflies we'd be in good shape! :-) H From: DPogue"at"mail.uttyl.edu I am working on a research project examining the distribution and ecology of bird blow flies (Protocalliphora) in Texas and Oklahoma. Protocalliphora larvae are ectoparasites of nestling birds, and have a high affinity for cavity-nesting species. Recent specimens of Protocalliphora have been collected from nests of several cavity-nesting species in Texas and Oklahoma. To determine the currrent distribution of blow flies, I need to collect nests (particularly those of cavity-nesting birds) from all areas of Texas and Oklahoma. If you are interested in collecting nests for this study, expenses for shipping and handling will be covered. If interested, please contact: Shelby Braman From: DPogue"at"mail.uttyl.edu Norma, Shelby Braman is a graduate student working under my direction at the Univ. of Texas at Tyler. This project on Protocalliphora is part of a collaborative effort with Dr. Terry Whitworth. The federal permit numer is MB701276-0. Darrell Pogue do you have a federal permit to have these sent to you? Norma Zier From: DPogue"at"mail.uttyl.edu We would like to thank everyone who has agreed to help collect nests of cavity-nesting birds for our study on the distribution and ecology of bird blowflies (Protocalliphora). We have decided to expand our study include Louisiana and Arkansas (along with Oklahoma and Texas). If you are interested in participating in this project by collecting nests of cavity-nesting species, expenses for shipping and handling of nests will be covered. This project is part of a collaborative study examining the distribution of Protocalliphora in North America. The federal permit number is MB701276-0. If interested, please contact: Dr. Darrell Pogue Shelby Braman Date: Wed, 30 Apr 2003 10:08:58 -0500 Ruth Brinckman First I just want to say that my mommy Blue has a total of six eggs in her nest. Oh happy day!! Keith's post on starlings and his mention of blowflies reminded me that I must prepare an emergency nest or two in the event that my bluebird nest becomes infested with blowfly larvae. One year I had a nest that was so infected that I couldn't remove all the larvae and I knew that these insects would suck the blood from the nestlings and eventually lead to a slow death. I removed the nest along with the nestlings in it and put it in a safe container. After cleaning any remaining larvae out of the box, I placed my "human made" nest in the box and put the nestlings in the new nest. I continued to monitor the nest closely and eventually all the babies fledged successfully. To make the nest, I took long dry grasses and weeds from a nearby field and simply shaped it into a nice tight woven nest. The parent bluebirds did not seem to mind, as they immediately went about their business feeding the babies as though nothing had changed. I felt so good about this, since a year or two before that I had nestlings die due to blowfly infestation. To check for the presence of larvae, I take a large old spatula and gently lift up the nest a bit. You can see the larvae crawling on the floor of the nestbox. From: "judymellin" judymellin"at"netzero.net Ruth- Please do not feel that my comments are directed towards you personally because they are not. I just very concerned when any of us put out Messages like this as if they are "gospel." No matter the reasons for what you do, it is illegal. The federal Migratory Bird Act prohibits any interference with the migration and/or nesting of migratory species. That means that, whether we feel we are "helping" the birds, we are still breaking the law. Further, on the subject of blowflies: this is information from Terry
Whitworth's paper on "Pathogenicity of larval Protocalliphora (Diptera: "Despite the presumed heavy blood loss, most nestlings are not killed by larvae of Protocalliphora. Studies of natural populations of Protocalliphora in 48 species of birds indicate that the larval populations are usually too small to kill or seriously injure most nestlings." So, if any of us choose to replace nests, move nestlings or eggs or interfere in the nesting process in any other way, we are, in my opinion, imposing our sensibilities on these creatures. I would think that, unless the bodies of the nestlings you lost last year were analyzed by a pathologist, there is no way to know why the young died. You might have seen what you consider an inordinate number of blowfly larvae in the nest or on the birds but there is no way to know if their presence was the cause of death. And, I fear, posts like this make others feel this is something they "should" do. I don't feel it is and I think we are wrong to let newer folks assume that it is. Judy Mellin ... From: "Zimmerman, Bet" I read from a TBN (Cornell) study that you need about 10 blowfly larvae per
nestling to have a serious problem (such as anemia). Maybe combined with another
problem it could impact them.... Might want to look at the nice table at
http://audubon-omaha.org/bbbox/bbtabl2.htm for figuring out what went
wrong.... Bet from CT ... From: "Zimmerman, Bet" The Bluebird Monitor's guide said that wire mesh doesn't always work that great with blowfly larvae because the parents push the nesting material down through it. What if you had a wire mesh square that you slid into a slot AFTER the nest was built (and placed the nest on top of it? How high off the bottom of the floor would it need to be? Bet Zimmerman Date: Mon, 21 Jul 2003 23:39:49 EDT ... I think this may well be somewhere back in the archives. Seems to me the idea was to have a thin plywood false bottom to the nestbox, which could be slid out from grooves and replaced with a wire/hardware cloth bottom. Wasn't there even a suggestion to have the wire bottom *only*? The idea being that the blowfly larvae fell through, of course, but also the drainage would be absolute, and in hot weather, more cooling. (The latter would have to have possibility of keeping a more or less solid bottom in northern areas, though, due to colder early spring conditions.) Rhonda Watts From: "Mary Beth Roen" mbroen"at"hotmail.com Hi everyone, When I first set up my trail, I put the wire mesh about 3/4 inch off of the bottom of the boxes, but the EABLs did just pack nesting material down below the mesh. I no longer use it. Mary Roen, River Falls, WI From: "Keith & Sandy Kridler" kakridler"at"1starnet.com Keith Kridler Mt. Pleasant, Texas Video in nestboxes has also shown that the larva of some of the blowflies are able to climb up and across glass or Plexi-glass partitions during filming of active bluebird nests. This would lead me to believe that the larva are easily able to climb back up an inch of wood if they happened to fall or were shaken out of the nest and through the wire when the female bluebird gives the nest a tremble thrust. On the other hand there is pretty good documentation of those who have compared long term the differences in using wire platforms in their boxes and the reduction of the blowflies. There is a complex set of variables with the wire platforms possibly making it easier for the parasitic wasps to find the blowfly pupa and attacking them when they have easier access to both the top and bottom of bird nests. The wire platforms may also allow the nests to dry out quicker and this may reduce odors or change the nest from one that blowflies might "prefer" to lay eggs in to one they would avoid. WHY did blowflies infest 6 of 9 Chickadee and titmice nests in my yard this year and avoid House Sparrow, Starling, Bluebird and wren nests? The Chickadee's and titmice used hair and fur and green mosses in their nests and were very tightly packed and blowflies were found in moderate numbers as were the parasitic wasps that prey of these flies. If you decide to use wire platforms keep good records and also use the 1/4" square mesh because the small eggs of chickadees will drop through the 1/2" wire that is recommended in some publications. KK From: "Karen Louise Lippy" brdbrain"at"superpa.net Our PA Parks has a meeting every year of all parks in the bluebird trails program. For the first few years that we went, we heard many people speak of blowfly infestations that killed all their birds. We had no problems with them. No early death. No sign of blowfly. Then the blowfly showed up one year and have been present ever since. So Linda may be correct that something is preventing blowfly from infesting your boxes other than the scrubbing. Eliminating blowfly larvae also eliminates jewel wasp larvae and I want all the jewel wasps I can get!! Karen from South Central PA ... From: Shane Marcotte marco50"at"bellsouth.net Karen, ... Latitude: 30° 27' North Longitude: 91° 08' West From: "Snook" dhsnook"at"sssnet.com Hi list, The blow fly lays eggs on a food source for the maggots such as road kill or young birds. On a trail with paired boxes, some have blow flies and some do not. Doug Snook NE OH ... From: "Karen Louise Lippy" brdbrain"at"superpa.net The complex biology of bird/blowfly/jewel wasp is very interesting. You've often heard of the 'web of life'. Well, here are 3 very interesting strands. Blowfly do not feed as adult flies. They seek out a bird nest, preferably with eggs close to hatch or newly hatched chicks. The eggs are laid in the nesting material. When hatched, they look like tiny maggots. But they can climb quite well. They move up through the nesting material and attach themselves to the chicks and draw body fluids from them. When full, they return to the nest material to rest until hungry again. After taking several meals and growing in size, the blowfly go down, often to the bottom of the box, and form a hard pupae. This looks a lot like rat/mouse droppings--a hard dark grayish oval-shaped object. If only a few blowfly larvae are in the nest, there is little lasting damage. The chicks replace the fluids almost as fast as they are drawn. But if there are a high number of blowfly larvae or another stress factor such as cold wet temperatures comes into play, the chicks often die. Enter the jewel wasp. The jewel wasp does not feed as an adult, but searches for blowfly larvae. The adult jewel wasp inserts an egg depositer into the body cavity of the blowfly larvae and deposits an egg. The jewel wasp larvae hatches and begins to feed upon the blowfly larvae. Blowfly continues its life cycle until it forms the pupae casing. Now jewel wasp larvae feeds on the essential organs of the blowfly killing it and emerges from the pupae casing and goes in search of a mate and then more blowfly larvae. Jewel wasps are only the size of a fruit fly and do not sting. They are highly beneficial to the birds because they eliminate blowfly. If I destroy the larvae before it hatches, I don't know if I'm destroying the good or bad insect. Amazing what we learn from looking after a small bird, isn't it? Karen from South Central PA From: "judymellin" judymellin"at"netzero.net Hi- Yes, we have a Cook County bluebird meeting every winter and most of the monitors complain about the blowflies they have. And every year I report on having none! It always turns out that these monitors do not scrub their boxes! Now, maybe I should a cause and effect from that but it seems to hit me right in the face that they don't scrub and have blowflies every year. I do scrub and have none! The idea of testing this has a great deal of validity but I would have to say that I am unwilling to have the nests/chicks that hatch on our site (not to mention ME!) subjected to the possibility of becoming infested when I have what I consider the way to prevent it. The hour I spend every year to scrub the boxes is well worth it to me! Maybe the scientific evidence would come when folks who do have infested nests and don't scrub decide to try the test you recommended. Terry's statistics have been published in scientific papers. I have one but cannot put my hands on it right at the moment. However, I think I can quote from memory that it takes far more blowflies than many folks are finding to cause problems. I'll post his stats when I find them. Judy Mellin From: "Keith & Sandy Kridler" kakridler"at"1starnet.com ... Jewel wasps:OK blowflies look very similar to a normal "house or barn" fly. While the predatory jewel wasps can actually lay almost 100 of their eggs inside a single fly and have most of them reach adults! These are tiny wasps! There are hundreds if not tens of thousands of different species of "jewel" wasps or those similar who feed on other insects in the same way. Some species of wasps lay eggs in adult aphids and these are plenty of food for these tiny creatures! You can take old birds nests that are not older than 7 days after fledging and break them apart on top of newspaper. If you find larva (maggots) of blowflies or the pupa (look like rat or mouse pellets) then you can build an escape proof container for the blowflies by covering the top of a five gallon bucket with an old window screen. Place the bucket with all the old nesting material and blowflies in an open carport or barn where the jewel wasps can hatch out and they are small enough to crawl through the window screen mesh and escape back into the wild while the blowflies will starve to death in a few days. If you have a lot of infested nests then you can use 55 gallon drums to keep the old nests in and simply use a larger window screen and weight it down to seal it tightly enough to keep in the flies. Remember that snakes and other predators will sometimes smell these old nests and will work their way into the containers!!! I bring home buckets of old nests and set them out of my truck at night and will dump them around my trees for mulch the next day. One year in a one week period I found three different snakes in the buckets come morning! KK From: "Zimmerman, Bet" At http://members.aol.com/birdblowfly/index1.htm it says "Infestation rates vary from almost 100% in magpies to 50% in many bluebirds, to zero in over 100 oriole nests (Whitworth & Bennett, 1992). In most areas, around 5-10% of infested nests are likely to have sufficient larval populations to make nestlings sick." Terry Whitworth's publications are listed as: Dawson, D.D., T.L. Whitworth, and G.R. Bortolotti, 1999. Bird blowflies,
Protocalliphora (Diptera Calliphoridae), in cavity nests of birds in the Boreal
forest of Saskatchewan. The Canadian Field - Naturalist, 113: 503-506. Whitworth, Terry L.1971. A Study of the biology of the species of
Protocalliphora in the northern Wasatch Range. Utah State University, Logan,
Utah, unpub. M.S. thesis, 58 pp. Whitworth, Terry L.1976. Host and habitat
preferences, life history, pathogenicity and population regulation in species of
Protocalliphora Hough (Diptera: Calliphoridae). Utah State University, Logan,
Utah, unpub. PhD. Dissertation pp. xii + 144. Whitworth Terry L.2002 Two new
species of North American Protocalliphora (Diptera: Calliphoridae) from bird
nests. Proceedings Entomology Society of Washington., 104: 801-811. Whitworth,
Terry L.2003 A new species of North American Protocalliphora ... Date: Thu, 31 Jul 2003 09:52:50 -0400 Haleya Priest Amherst MA From: "Rudy Benavides" rbenavid"at"hotmail.com I think the purple martin folks have done a great job on their website showing pictures and descrbing the life cycles of these parasitoids. I especially like the picture of the Nasonia (jewel) wasps emerging from the blowfly pupal case. Warning.... not for the squeamish about bugs. http://www.purplemartin.org/update/Parasites.html ----rudy/maryland From: "Keith & Sandy Kridler" kakridler"at"1starnet.com Keith Kridler Mt. Pleasant Texas Some species of ants live in the bottom of the nest just under young birds while other species of ants attack and eat the baby birds. Maybe ants or ant scent would deter blowflies from laying eggs in the first place. I know we can gather enough fire ants in the south to mash and make a water spray to treat our nestboxes with their scent and this might also make a fun experiment for some trails where blowflies are a major problem. There is no need to separate the blowflies from the nesting material and many loosely packed nests can be placed in a screened over container and the blowflies and jewel wasps will come to the top where there is light coming into the container. I believe there is more need to simply allow nature to take her course and we probably do more damage by destroying old bird nests than we do good. For those with severe blowfly infestations on their trails there is some evidence that using insecticides in nestboxes actually kills more jewel wasps over a longer period than blowflies since the flies are far larger and more resistant to residual amounts of commonly used chemicals. .... KK From: "Zimmerman, Bet" If you haven't seen it, there is a really good website at http://www.purplemartin.org/update/Parasites.html on bird parasites. Good section on blowflies and photos. Some gross stuff - e.g., " If we were to view blowfly parasitism from a human perspective (which is improper to do), it would be like trying to sleep in your bed at night with dozens of pickle-sized, bloodsucking maggots intermittently feeding on you!" Bet from CT From: "Burnham, Barbara" Barbara.Burnham"at"zzz.zzz Shane, Here is a web page that discusses the relationship between blowflies and
jewel wasps.
http://birds.cornell.edu/birdhouse/getting_started/nestwhat'shappening.html
Barbara Burnham From: "emcooper" emcooper"at"bayou.com My husband tells me that they will come in a heartbeat if they turn on a valve to a butane tank. I wonder if they can smell the terrible odor that the butane puts out. I am not bothered with blowflies on my trial even though we do have them. Evelyn Cooper Delhi, La. Louisiana Bayou Bluebird Society Bluebirds along the bayous.....where we lend a helping hand! www.labayoubluebirdsociety.org From: Cher [mailto:bluebirdnut"at"a-znet.com] I had two nestings of TRES going on in my yard simultaneously this year, one in a wooden box on the north side of the house, the second in a PVC box on the south side. This is my fourth year with nesting Blues/TRES, and I have never witnessed any problem with blowfly before. Yesterday, I found that the five babies in the nest on the north side of the house, in the wooden box, had fledged, 20 days after incubation began. The other nesting was a few days behind the first, but it seemed awfully quiet for a nestful of babies about to fledge, so I ventured to check, even though it was Day 15 for them. What I found made me feel ill: four perfect little nestlings -- dead -- and blowfly larvae in the nest and under their wings. When I last checked the nest (last week) there was no sign of anything being amiss, and even when I looked in yesterday, I couldn't see any sign of the blowfly until we removed the nestlings and nesting material. The nest was not especially dirty -- indeed, the wooden nestbox across the yard was a great deal filthier than this one, although that might be because these babies weren't quite as old. I saw no other signs of anything that could have hurt these babies -- no pecking, no damage. There are no pesticides in use, because the pasture to our south has sheep/horses/donkeys grazing, right up next to the fence that separates the properties, and the nestbox is only about five feet from that fence. There may have been some mites, because I felt itchy after cleaning up the box, but that could have just been "in my head" (not literally, hopefully!). There were about 2-4 larvae under the wings of each of the birds, and several more in the nesting material. It didn't look like they'd been dead very long. I posted photos of them on my Message board at http://p202.ezboard.com/fbluebirdnutcafefrm2.showMessage?topicID=482.topic; also at my website at http://www.bluebirdnut.com/Predators_Pests.htm Really gross question: Do blowfly larvae ever actually burrow into and take up residence inside the body? Because as my DH and I were trying to get these photographs, the little devils kept disappearing on us, and we could have sworn they were disappearing into some opening they were making in the bodies. Ugh. I'm starting to feel crawly again. My concern is, I have a second nesting of Bluebirds begun in another PVC box on the same side of the property -- this is the same box that was used for their successful first nesting. I'm going to need to monitor it carefully for blowfly, but it isn't easy monitoring a PVC box without actually removing the nestlings bodily to check. Any ideas, suggestions? Cher From: Cher [mailto:bluebirdnut"at"a-znet.com] A few people have indicated that perhaps the blowfly infestation I had in my TRES nest was not extensive enough to have killed the babies, and I'd like any comments, ideas, suggestions anyone might have on this subject, as I have a second nesting of Bluebirds started in the same type of nestbox (a PVC box) not twenty feet away. It was hard to get an accurate larva count, because originally I disposed of the nestlings and the nesting material, then thought better of it and pulled them out to take the photos I posted to my forum. But I would guesstimate that each nestling had from 2-4 larvae under their wings, fairly large ones, as you can see by the photos (http://p202.ezboard.com/fbluebirdnutcafefrm2.showMessage?topicID=482.topic - for those that didn't see them) There were more larvae in the nesting material -- maybe a dozen or so large ones, and more tiny ones. >From what some folks are saying, it appears that this is not usually considered a "lethal" infestation. Some have suggested that perhaps the blowfly moved in after the babies died of some other cause, but I don't think that could be the case because of the size of the larvae on the babies, and the condition of their little bodies -- they hadn't been dead very long. There may have been some mites, because I felt kind of crawly when I was finished with the cleanup, but I didn't SEE any mites, and it could have been just a mental thing -- it was all very gross and disgusting. I had seen the babies just a few days before, and they were fine. I'd stopped checking the nest around day 12/13, as I usually do for the Bluebirds. Perhaps I should have kept up the vigil a bit longer, as they usually take a little longer to fledge? I don't think pesticides are an issue, as our property abutts a pasture where there are sheep, horses, and donkeys grazing -- I don't think the farmer would use pesticides in a field his animals are grazing in. There was no sign of pecking, although someone suggested that a HOSP might enter the nest and break the nestlings necks without doing any visible damage. But I had a spooker on this nest, and hadn't seen any HOSP messing with it, although I do have a couple of rogue males that I have been unsuccesful in trapping. I suppose it's possible that something happened to one of the adult birds -- but BOTH of them? I have TRES all over my property, so there's no way of sorting out who's who. So, I am out of ideas. I know the mystery will probably never be solved, but I'd like to hear any ideas anyone has. I do know that I will be very closely watching that Bluebird nesting! Cher From: Paula [mailto:PaulaZ"at"columbus.rr.com] Cher, Sorry to hear about your TRES disaster. I lost a nest of them on my trail a couple of weeks ago as well. There were no blowfly larva in my nest and no marks on the babies. My nesting material seemed a bit wet and I attributed my loss to possible hypothermia. Another possibiltiy is always that something happened to the parents and the babies subsequently starved so always look for parents when monitoring boxes. I have had blowfly larva in EABL nests before, but never in TRES nests and don't know why. Also, blowfly larva have never killed any of my birds, not due to anything special I did, but due to them not killing their "host" I imagine. The only measure I have ever taken with the larva is to gently raise nest off the floor with a putty knife about an inch or two. Then I scrape any larva I see that are on the floor onto the ground. I don't know if the number of larva you describe is a lot or not. Hopefully others can comment on this too. The possibility of disease in my nest and/or yours is also a possible cause of death too. Paula Z Powell (Central) Ohio From: Paula [mailto:PaulaZ"at"columbus.rr.com] Cher, I just reread your post and got to thinking. Are you certain the insects you saw were blowfly larva? I am assuming you were looking in the box during daylight hours and blowfly larva feed at night I believe. You also mentioned that the larva were crawling into the nestlings and disappearing. >From what you have described, you may have maggots eating the dead nestlings. Blowfly larva merely suck some blood out of the nestlings and don't actually eat them. Other flies (not blowflies) may have laid eggs on dead babies and maggots were eating them. You can see some pictures of blowfly larva at: http://www.americanartifacts.com/smma/per/b5c.htm to compare with what you saw. Hopefully Keith or someone else who knows their insects better will comment further on this, but for my two cents: yuck.. yuck.... Paula Z Powell (Central) Ohio From: Joe Huber [mailto:hubertrap"at"webtv.net] Hi Cher and all, Those pictures of blow fly larva on dead bluebird babies should convince you of the cause of death. The Adult blow fly lays eggs inside the bluebird nest box in the nesting material. They later hatch and attach themselves to the baby bluebird body,where they suck blood to live on. If enough blood is lost the bird dies. This is not because of nesting material used by the parents,but simply from where the adult blow fly chooses to lay eggs. In some locations there is very little problem from blow flies. Some years are worse that others. This is a natural phenomenon and generally of little concern. Later nests should be less effected. Best wishes Joe Huber,Venice Florida From: Tina Phillips [mailto:cbp6"at"cornell.edu] Hi Joe, Some of you may recall the work that Dr. Terry Whitworth did in conjunction with TBN on blow flies in the nest. According to his estimates, a nest with more than 10 blow flies per nestling is considered an infestation and could weaken the birds enough to cause death. Tina Phillips The Birdhouse Network From: Bet Zimmerman [mailto:ezdz"at"charter.net] I've had blowflies in both tree swallow and eastern bluebird nests. Have not noticed them in chickadee, titmice or house wren nests... Bet form CT From: Kerry Sweet [mailto:ksweet3450"at"yahoo.com] Cher, Tina is right and At one time you could send your old nests to Terry Whitworth and he would examine them and let you know his findings. I have sent old nests to him before. I think he could tell you anything you ever needed to know about Blowflies. Below is his website which is very informative. http://www.birdblowfly.com/ http://www.birdblowfly.com/ Kerry in NE corner of Okla. From: judymellin [mailto:judymellin"at"netzero.net] I believe that, a couple of years ago, he indicated that he did not need any more nests from cavity nesters but would like them from other species. He does have a federal permit number to collect and analyze so, if any of you find nests that are a bit "out of the ordinary," I think he would be interested. He analyzes them very quickly and will give you a complete report of what he finds. Judy Mellin NE IL. From: KCBSP"at"aol.com [mailto:KCBSP"at"aol.com] Isn't that interesting? Think it's true? Anybody know about that.. Why wouldn't they rehatch and stay inside the liner? It doesn't sound right to me but that's just me.. I have replaced the nests but the blowflies come back sometimes anyways in the new nests especially if it's hot. Kathy Clark, New Cumberland, PA From: G McCall [mailto:gmccall"at"rochester.rr.com] All five of my baby EABBs have died. Now I understand why they were on the ground, there was an infestation in the box, and the parents made them come out early. They were so close at 19 days old. I was told not to open the box after 11 days so that the young would not fledge early, but obviously to check for blowfly larvae I should have. I have been doing some reading about blowflies but I have not seen much about preventing them. I read about placing a screen 1/2" above the nest box floor after the nest is constructed. I also read that the nest should be changed when there is evidence of larvae. Anyone have experience/success with these methods? Is there anything else that can be done? How do these birds survive in the wild? This is my second unsuccessful nesting and it's becoming frustrating. From: Lawrence Herbert [mailto:lherbert"at"4state.com] Sent: Tuesday, May 24, 2005 10:29 PM Subject: blowflies/ KS & MO Tree and Bluebirdsters: I have experienced very little blowfly infestation in EABL nests in Kansas and Missouri in my 30 years experience. I make a note of them if they are observed in the nest and/or when I'm taking out an old nest. Last year I sent 60 or more used nests to a person researching parasites to Tyler TX. So, here in KS and MO we haven't experienced the trouble that some people have reported in the east and northeastern U.S. Good birding, Larry H. Joplin MO. From: Paula [mailto:PaulaZ"at"columbus.rr.com] Sent: Tuesday, May 24, 2005 10:26 AM Subject: Re: Preventing Blowflies? Gordon, I'm sorry this happened. Blowflies feed on the chicks' blood at night and then burrow down into the nesting material during the daytime. During daytime nest checks, you can check the chick's feet for evidence of bites and you can gently lift up the nest and look for blowfly larvae on the bottom of your box or in the nesting material. If you find a lot in there, you can replace the nest with one fashioned of dry grass. I have only replaced a nest once due to blowfly infestation in a neighbor's box. I often find evidence of blowflies in my boxes, but seldom what I would term an infestation. My neighbor had a lot of them and the nest was damp so I replaced it. The parent EABL's accepted this new nest with no difficulty and all their chicks fledged fine. There are mixed reviews regarding the 1/2" mesh hardware cloth on bottom of box. Some think it helps. Others do not. I wouldn't bother with it personally, but would not hesitate to replace a nest that I believed was infested with blowflies. Paula Z From: Tree Greenwood [mailto:doctree"at"crosslink.net] Sent: Wednesday, May 25, 2005 11:23 AM Subject: Re: blowflies/ KS & MO -- & PA, NY & OH & beyond Larry, that's a confirmation of Terry Whitworth's research. He found almost 100% of nests from NY, PA and OH infested. Less than 1% of nests from TX contained any evidence of blowfly larvae, the lowest incidence in his earlier study. Gordon was caught unaware that he was in an area with a high incidence of infestation. Monitors in New York, Pennsylvania and Ohio need to be most vigilant. Those in surrounding states need to watch carefully, too. Infestations will vary greatly there. Those in the midwest, especially southern midwest, are relatively safe... for now. Did the folks doing research in Tyler TX also check for evidence Jewel Wasps? It would be interesting to know if parasites that prey on blowfly larvae are keeping blowflies in check or if it's weather conditions or something else. Take care, R J 'Tree' Greenwood From: Keith & Sandy Kridler [mailto:txbluebirder"at"sbcglobal.net] Sent: Thursday, May 26, 2005 8:13 AM Subject: Re: blowflies/ KS & MO -- & PA, NY & OH & beyond Keith Kridler Mt. Pleasant, Texas I drove about 1,200 miles through North and South Carolina this past week. There are vast differences in how our Eastern Bluebirds need to cope with weather and predators and there is also a vast difference that the different species of Blowflies have to cope with across the country. I have participated with blowfly research with DR. Ben Pinkowski in the 80's, Dr. John Werren in the 90's and Dr. Terry Whitworth in 2000's and Terry oversaw the work of the Texas student. Everyone should and can look for blowflies in their old nests!!!!!! EVERYONE can easily save the blowflies pupa and check for the presence of Jewel Wasps, a good predator of blowflies. Blowflies are more likely in my area to be found in old chickadee nests, titmice nests and probably Prothonotary Warbler nests as they use tightly packed and moist building materials and they nest early in the season when temperatures are cooler. Almost 100% of chickadee nests have blowflies in my area of Texas some years. Why don't the bluebird nests have more? Chicken and dairy farmers buy jewel wasps and release them for fly control in some areas. I am just down wind from a huge dairy area and in the middle of hundreds of millions of broiler chickens. Look up blowflies to identify their pupa, look up jewel wasps, keep track of how many nests you have and how many nests contained blowflies and you can run your own research:-)) There are LOTS of really important research that bluebirders can do to help us understand this incredible world we live in. To save Jewel wasps, old bird nests should be saved in containers that will contain a House Fly sized insect but covered with normal window screen wire mesh and stored where the jewel wasps can hatch out of the blowfly pupa, crawl through the screen mesh and then fly off outside. There are literally tens of thousands of "Jewel" wasps species around the world, many that you can barely see with the naked eye! KK From: jwick"at"tds.net [mailto:jwick"at"tds.net] Sent: Friday, May 27, 2005 11:22 PM Subject: Re: blowflies/ KS & MO -- & PA, NY & OH & beyond Although we've had a cool spell recently, I am finding quite a few blowfly present in the bases of the majority of my bluebird nests this spring. Normally, I do not find this many blowfly larvae present until later in the nesting season (July+August.) I'm curious as to what the cause of this might be. ~Ann Wick, Black Earth, WI From: agriffee [mailto:agriffee"at"adelphia.net] Saw the post about blowflies. Am I supposed to check for blowflies? Can only see the top of birds, top of head and back feathers. Birds are 13 days old today. What do you do pick them up and look under wings? Are there signs that prompt one to check. I'm dying to touch these birds! Have not because thought wasn't supposed to. From: Lana Hunt [mailto:lanahunt"at"kcp.uky.edu] Arnold, my boxes are front opening so I can see the front of the bottom of the nest. I have not seen blowflies personally, but have read and heard about them on this list. I think they stay under the nest and come up at night and nourish themselves off the babies. Someone more experienced will give you advise about that. I just wanted to tell you I have stroked the babies with my finger, I have never picked one up; it didn't seem to cause any harm. Mom wasn't sitting on them at the time of course. *she might have objected* But the myth that if you touch a baby bird the Mother will abandon it, is just that; a myth. I don't think birds can smell that well? Lana From: Bruce Burdett [mailto:blueburd"at"verizon.net] Arnold, Lana, et al, From: Kate Arnold [mailto:koscharn"at"cox.net] Sent: Saturday, June 18, 2005 10:19 AM Subject: RE: Checking, counting, etc. Please don’t take this as a criticism of anyone who handles baby bluebirds. Just to show the flip side of the coin, I never pick them up. It is not that I don't feel capable of handling them gently, I just feel like the less handling they receive, and the “wilder” they stay, the better for them in the long run. Of course, if there were some sort of problem, I would do whatever handling was necessary, but my monitoring is generally a quick look in the nest. If the babies are hard to distinguish and count, I confirm the count a few days later when the individuals are more distinct. Kate Arnold From: Dottie, Hickory Hollow, Brown County, Indiana [mailto:yumyumkatts"at"voyager.net] Sent: Saturday, June 18, 2005 11:35 AM Subject: Re: BB Checking, counting, etc. I do the same. I don't pick them up either unless I think there is a We can have 3-4 nestings here. I'm hoping for a third nesting this year. Dottie, Hickory Hollow From: Paula [mailto:PaulaZ"at"columbus.rr.com] Sent: Wednesday, June 22, 2005 10:31 AM Subject: Re: Checking, counting, etc. Just a little note (from experience) for those planning to handle chicks for short time before replacing in the nest. Don't put them on any type of material (cloth) as their little toenails hook into the material. It could be a bad situation. Bruce's suggestion of dried grass is a good one. If others have preferred materials, it would be good to hear. Paula Z From: B.Grillenberger [mailto:B.Grillenberger"at"rug.nl] Sent: Wednesday, June 29, 2005 2:38 PM Subject: old bird nests from Utah Dear Bluebird people, I am a PhD-student from Groningen University (The Best regards Bernd Grillenberger, b.grillenberger"at"rug.nl From: Keith & Sandy Kridler [mailto:txbluebirder"at"sbcglobal.net] I really don't think we have any bluebirders on this list who post from Utah. Terry Whitworth would be the one to contact in Washington as he has studied these parasitic wasps for many years and might have some contacts in Utah. Most of these would be Western Bluebirds. Does anyone on the list have a current e-mail address for Terry? Keith Kridler Mt. Pleasant, Texas From: charlene anchor [mailto:charleneanchor"at"msn.com] Charlene Anchor From: Sara Ann [mailto:sawright"at"direcway.com] Sent: Saturday, February 18, 2006 2:00 PM Subject: Re: Bird Watcher's Digest story and use of Bay leaves I've read about using bay leaves in flour and cornmeal to keep out mealbugs. It's worth a try! From: Keith & Sandy Kridler [mailto:txbluebirder"at"sbcglobal.net] Sent: Thursday, March 23, 2006 9:27 AM Subject: wire platforms under bluebird nests Keith Kridler Mt. Pleasant, Texas There are several species of blowflies that feed on bird nestlings in different parts of the country. There are a dozen or more different species of tiny parasitic wasps if I remember right that in turn feed on the pupa of these flies. Nestbox cameras have shown that blowfly maggots can climb up from the bottom of these boxes and they have even been shown to be able to climb up a glass wall of a nestbox so the air gap the wire platforms create do not kill the blowfly larva! BUT the platforms help keep the nests drier, they also allow the tiny parasitic wasps to have better access to the whole nest and possibly find more of the pupa quicker. They may also allow a space for different species of spiders to live in the nestboxes and some of these might feed on adult blowflies or their larva. Dr. Terry Whitworth worked with these blowflies and their predators for years and says that blowflies also feed on many species of birds that use open nests in trees and bushes and these don't fall out and perish either. If you use the wire platforms under your nests be sure and use 1/4" square mesh or even 1/8" square mesh as I have found that chickadee eggs can work through the bottom of a shallow nest and fall through 1/2" square hardware cloth platforms! There are companies that sell the parasitic wasps for fly control in dairy barns and horse barns and for poultry houses. I just got a booklet from www.spaldinglabs.com located in Arroyo Grande in California they claim to have been shipping these for 30 years. Back in the 1980's many of the dairy farms used these in our area. When sending in nests for blowfly research over three different decades each time the researchers found parasitic wasps thinning out the rare blowflies found in nests along our trails. I am not promoting buying these wasps as they occur naturally all over the country but this is one reason to limit the use of insecticides in your boxes. The wasps or ants you treat with insecticides this spring might still be potent enough to kill or repel beneficial insects or spiders later this summer. KK From: melissa fox [mailto:meberle2"at"hotmail.com] Sent: Thursday, March 23, 2006 9:49 AM Subject: RE: wire platforms under bluebird nests Thanks for the info! My husband is building my first bluebird box and I wanted to put the wire mesh in just in case it did help any. I also figured if nothing else it would help with ventilation keeping the nests dry. My only concern was during the nest building process........would they grasses they accumulate just fall through the mesh? I'm not sure what size ours is......I thought they were all the same size. Good thing you posted this before we installed it. I had also heard that the parasitic wasp is almost wiped out in most parts of the country(?) It might be something worth looking into though. .... -Melissa from Columbus From: Mary Beth Roen [mailto:mbroen"at"hotmail.com] Sent: Thursday, March 23, 2006 12:56 PM Subject: RE: wire platforms under bluebird nests Melissa, For the first few years on my trail, I used the hardware cloth mesh on the bottoms of my nest boxes. In my experience, the nesting material did fall through the mesh and was solid under it, so it didn't seem to help any. There was no open space under the nest. I no longer use these in my nest boxes. However, I used 1/2 inch hardware cloth so maybe the smaller sized hardware cloth would prevent this from happening. Mary Roen, River Falls, WI From: kingston [mailto:kingston"at"cstone.net] Sent: Friday, March 24, 2006 6:51 PM Subject: Re: wire platforms under bluebird nests Keith, Talking to Ira Campbell of Timberville, Virginia a while back; he says that he started with and has always used 3/8 hardware cloth (no other size worked for him) and does get credit for placing a hardware cloth raised platform in the bottom of a nestbox. For years he has received international calls about his idea. Ron Kingston Charlottesville, VA From: kingston [mailto:kingston"at"cstone.net] Sent: Friday, March 24, 2006 7:17 PM Subject: Re: wire platforms under bluebird nests What follows is an archived (1999) email of mine From: Ron Kingston <kingston"at"cstone.net> Date: Friday, February 05, 1999 11:34 PM Ron Kingston, Charlottesville VA, near the Blue Ridge Mountains There is some misconceptions out there about the raised mess floor to deter blowflies. My good friend Ira Campbell of Timberville, VA designed the floor back in the late 70's(check your old Sailias). We only use 3/8 hardware cloth(rabbit cage wire) here. One half (1/2)inch allows too much nesting material to fall through (Chickadees eggs too), but allows the blowfly larvae to past through. If bluebirder here in Central Virginia have sparrows, we "Trap". I understand from some bluebirders that Steve Gilbertson's PVC box has had good success here also. Ron Kingston Charlottesville VA North American Bluebird Society Speakers' Bureau Chairman From: Perez Veronica [mailto:v_perez11"at"yahoo.com] Sent: Friday, May 26, 2006 9:35 AM Subject: Box flooring to prevent bowflies I just ordered my gilbertson box. Is there something i Continued on Blowflies, Part 3 |
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