I was curious what the literature said about stable fly breeding.
From https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4722882/
Ovipositional substrates contain decaying vegetation, excluding dung unless it is comprised of or mixed with vegetation or dropped onto vegetation.2 The substrate must be moist, and fermentation of the plant matter is particularly conducive for larval development.3 Examples of substrates in which the pest develops include decaying hay, alfalfa, silage, sugarcane, beached sea grass, lawn cuttings, compost, and piles of waste vegetables.2,3,5–8 Cattle manure, however, is sometimes utilized by stable flies for oviposition, particularly on mid-western US cattle feedlots, where high summer temperatures cause exposed manure to dry and develop a crust on the surface, sealing moisture within, thereby creating a relatively long-term, insulated habitat.2,6 Similarly, buildups of equine manure mixed with straw, particularly around stables, are also important developmental sites, but unaltered deposits of cow, horse, and sheep dung are less conducive.3 Typically, a female will lay eggs on 4–5 occasions, up to 20 times, and 60–800 eggs can be produced during the life of a female.1,2
Eggs hatch in 2–5 days at 26°C, and higher temperatures can reduce that period to ~12 hours.1,2 Emergent larvae, or maggots, bury themselves in the oviposition substrate to feed and to prevent desiccation.1 After 12–26 days (12–13 days at 27°C), third instars enter the drier parts of their habitat and pupate.1,2 Most pupae produce an adult in 5–26 days at 21°C–26°C, and the imago is ready to fly in less than one hour.
I bolded the parts that seem relevant to us here. These are the areas that bti can be effective in.
When I spray, I cover:
- entire chicken run (stonedust & dirt, no bedding, chicken poop is not removed, ~15'x50')
- grassy/weedy edges just outside the chicken run
- poop bucket that sits outside the chicken run, for coop poop
- horse stalls, lightly spraying clean bedding and more heavily spraying stall edges and around water tubs
- muck cart, heavily spraying the days poop and soiled bedding
- manure pile
- around the field troughs
Doing all this yesterday, I went through ~3 gallons of my 4 gallon sprayer (misrecalled the size earlier in the thread!)
Most of those are pretty obviously potential spots for breeding flies. I hit the clean bedding thinking that might be useful once it’s soiled and moved to the manure pile (kind of pre inoculating it with bti.)
I also have fly traps–the hanging ones–around the edges of the barn yard. It helps me figure out where flies are coming from…is it the manure pile producing them, or the chicken coop? Or somewhere else? It’s not fool proof, but it provides some direction on where to focus.
Fungus gnats reproduce in similar environments. From http://ipm.ucanr.edu/PMG/PESTNOTES/pn7448.html
Fungus gnats develop through four stages—egg, larva (with four larval stages or instars), pupa, and adult. The tiny eggs and oblong pupae occur in damp organic media where females lay eggs and larvae feed. At 75ºF, eggs hatch in about 3 days, the larvae take approximately 10 days to develop into pupae, and about 4 days later the adults emerge. A generation of fungus gnats (from female to female) can be produced in about 17 days depending upon temperature. The warmer it is, the faster they will develop and the more generations will be produced in a year.
Most of the fungus gnat’s life is spent as a larva and pupa in organic matter or soil, so the most effective control methods target these immature stages rather than attempting to directly control the mobile, short-lived adults. Physical and cultural management tactics—primarily the reductions of excess moisture and organic debris—are key to reducing fungus gnat problems.
Because fungus gnats thrive in moist conditions, especially where there is an abundance of decaying vegetation and fungi, avoid overwatering and provide good drainage. Allow the surface of container soil to dry between waterings. Clean up standing water, and eliminate any plumbing or irrigation system leaks. Moist and decomposing grass clippings, compost, organic fertilizers, and mulches are also favorite breeding spots.
In my barn, it’s the damp bedding that builds up behind the water tubs that really drives the gnats, so making sure to hit those spots helps considerably. They’re poor flyers, so it’s usually pretty easy to find the damp areas that contribute to those populations.
I hope this helps identify areas to target!
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