[Bluebird-babble] Blowfly evidence in bluebird boxes

[dave-mueller at comcast.net]

WHERE IS CHEROKEE RANCH?
 -------------- Original message ----------------------
From: "Robin Bartlett" <robart49 at earthlink.net>
> Kathy, caught your email about blowfly infestation. I am monitor at Cherokee 
> Ranch and have not noticed any undue numbers of pupae in boxes nor chick death 
> associated to blow fly. Usually I see the worst in wet humid conditions with 
> feces compacted nests. That's why I tend to remove those ugly nests and hope the 
> parents will rebuild a clean nest for 2nd broods. Overall, removing the 
> compacted nests usually benefits us with a 2nd hatch. I'll tell you in my 10 
> years of monitoring I have never ever seen larva on the chick body either. I 
> think the information is true-they come up at nite and attach to legs so as the 
> parents can't pick them off. I do look at chick bodies when conditions are ripe 
> for blow fly and can't find them. We have conducted counts of blow fly pupae per 
> nest and I found when there were over 50 in the nest plug I might see a chick 
> death or more. 
> 
> I have associated  increased Diptera concentrations with long wet springs. 
> Bottle or Blow Fly deposit over 1,000 eggs per whack and they need heat and 
> humidity to hatch but just as important they need the manure to lay the eggs in.  
> What box (type) construction do you have? You could try removing the feces laden 
> compacted nests just after fledge of 1st brood or put pine needles under cleaner 
> nests each time you visit especially after hatch of first brood. The pine resin 
> is a known natural insecticide that's what supposed to do them in or slow them 
> down. Even if blow fly are sucking the chicks blood be aware the chicks are a 
> hemoglobin factory. They can support some insult to their hematocrits. Maybe 
> there is another disease actually killing the weakened chicks? Do you note any 
> whitish areas on the dead chicks? I
> 
> If you decide to keep a so so looking nest take a plastic bag  and shake out 
> larvae/pupa. You could also support the nest off the bottom of box with wire 
> mesh...make it harder for the nasties to crawl up to chick. It is the larva you 
> really need to sweep out. The pupa are the last gestational stage for 
> overwintering  or till next cycle whereby the fly pops out and starts all over. 
> That whole cycle takes about 4 to 5 weeks.
> 
> I look at the depth of the nest constructed by the BB parents. Generally the 
> thinner ones (around 11/2" to 2" thick) are set ups for lots of fecal compaction 
> and hence the fresher thicker manure for adult flies to lay eggs. Have you 
> noticed some BB parents just can't keep up with the fecal sac disposal system? 
> The BB that can build deep thick nests and work hard to remove the fecal sacs 
> don't have as high blow fly larvae/pupae. If you see nests with around 20 to 25 
> pupae at end of season bet they won't have chick death from larvae. 
> 
> I would advise watching how the chicks look in the box. Do they seem lethargic? 
> Won't raise their heads when you whistle. Seem too weak to take food. When I see 
> that it could be 1) excess temperatures, 2) blow flies, 3) poor feeding by the 
> parents,4) or  disease. I guess you have to take in what conditions your chicks 
> are facing and eliminate those previous options and make a judgment as to cause.
> 
> PS If you do remove the first dirty nest I would not advise putting any dried 
> grass in to "help the birds along" with a 2nd nest construction. I believe it 
> 'puts the birds off' and they think another pair has claimed the nest. Then the 
> box never is renested.
> 
> Hope this helps, Robin Bartlett
>   ----- Original Message ----- 
>   From: KathyDressel at aol.com 
>   To: Bluebird-babble at denveraudubon.org 
>   Sent: Friday, July 18, 2008 10:40 AM
>   Subject: [Bluebird-babble] Blowfly evidence in bluebird boxes
> 
> 
> 
>   I have cleaned out quite a few bluebird nestboxes on the Winkler Ranch and at 
> Castlewood Canyon State Park.  I have noticed alot of blowfly pupae in the 
> bottom of  at least 90% of those nests.  This is the first year that I have 
> noticed such a huge presence of  this insect.  I also noticed them in the bottom 
> of two of the nests I removed from boxes on my trail in Franktown (Deerfield).
>   I know that this was a good year for insects (weather-wise) in our area. I was 
> wondering if anyone else has noticed the presence of blowfly larvae or pupae.  
> There have been several boxes in which I found dead nestlings.  I think that now 
> I know the cause of their deaths.  I never did see larvae on any of the young, 
> but the boxes are dark and I do not remove the nestlings to really examine them.
>   If the weather repeats itself next year, I am thinking of doing preventative 
> maintenance on my three trails.  I will wait until the nests have been built  
> and eggs have been laid, and then I will place a sprig of pine needles in the 
> bottom of the boxes by gently raising the nest with a putty knife.
>   Has anyone else noticed this?  Any ideas?
> 
>   Thanks,
>   Kathy Dressel
> 
> 
> 
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From: "Robin Bartlett" <robart49 at earthlink.net>
Subject: Re: [Bluebird-babble] Blowfly evidence in bluebird boxes
Date: Fri, 18 Jul 2008 18:15:10 +0000
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