Flies can be a headache any place livestock and poultry abound, but even the smallest urban henhouses attract flies. Sometimes lesser species such as stable flies, blow flies or soldier flies take up residence in poultry yards. But major nuisance bugs found most everywhere chickens reside is the common housefly (Musca domestica).
Adult houseflies are 1⁄4- to 9⁄32-inch long. They are gray to black, with four narrow stripes on their somewhat hairy bodies and a single pair of transparent wings. They have red eyes, set farther apart in the slightly larger female. Males have longer legs.
They are extremely hardy and thrive all over the world wherever humans are present, including as far north as the Arctic Circle. They don’t bite humans or animals. But they do carry parasite eggs and spread disease the likes of avian influenza, botulism, salmonella, E. coli and Newcastle.
And their buzzing annoys poultry and people alike.
Houseflies are active by day and rest at night, when they tend to congregate on ceilings, beams and overhead wires. Outdoors, they crawl into long grass or rest in shrubs and trees.
A major problem is that houseflies reproduce so freely. Each female lays from 75 to 200 eggs per cluster at three- to four-day intervals, depositing them in fresh manure (less than 1 day old) or in manure mixed with damp bedding or similar organic materials including wasted chicken feed. In her lifetime, a typical fly produces 350 to 900 eggs.
Larvae, called maggots, hatch in 12 to 24 hours and begin feeding, completing their development in four to seven days, when they move to a drier location at the edge of their breeding habitat and morph into dark reddish-brown pupae. The pupal stage lasts a few days to four weeks, depending on temperature and humidity, then adult flies emerge.
Under ideal conditions, a complete life cycle can occur in seven to 10 days.
No one fly-control method works 100 percent. But by combining several, you can keep your coop reasonably fly-free.
The most important thing is to remove droppings regularly, ideally once a day but several times a week for certain. Sanitation is everything in fly control. Move manure away from the chicken house, and spread it out to dry. Or compost it if you prefer.
Use absorbent bedding, but I wouldn’t use straw. Dirty or damp, straw is a favorite breeding ground for houseflies. Sand is a better choice for coop bedding and to use in your chicken run. It coats droppings and dries them out, while helping absorb odors.
Droppings stay on top of the sand. There, they’re easily removed with a section of hardware cloth.
Replace or repair leaky waterers. Remove feed spills and any feed that has gotten wet. Dead birds and broken eggs should be disposed of quickly and as far from the chicken house as possible.
Traps, Tapes & Screens
Electrocuter light traps (“bug zappers”) are effective against flies. But they’re costly and kill beneficial insects such as moths as well.
Old-style sticky tapes do a decent job in small coops and flytraps are good most anywhere. Make your own traps or buy commercial traps, and hang them according to the manufacturer’s recommendations. Monitor them on an ongoing basis and replace as needed.
Consider window screens and screen doors for smaller coops where the cost isn’t prohibitive.
Fly predators are gnat-sized, nocturnal, stingerless wasps that lay their eggs in fly pupae. A female wasp searches manure for pupae. When she finds one, she drills a hole in the pupa case and lays several eggs inside.
As the eggs develop, immature wasps feed on the fly larva as a food source, and then emerge from the pupa in a week or two. Each female fly predator kills about 100 pupa-encased fly larva in her lifetime.
Several species of fly predators are available commercially and identifiable by their Latin names in ads and brochures. The best for housefly control is Spalangia nigroaenea, which also helps control biting stable flies.
Companies selling fly predators provide guidelines to calculate the number of wasps to use. They don’t reproduce in sufficient numbers to control aggressive fly populations. So during fly season, parasitic wasps must be replenished about once a month.
Bugs on Birds
Even more difficult to deal with than flies are those nasty little parasites that live on chickens. Think: mites, lice and sticktight fleas.
Does your chicken have them? Flip her over and ruffle through her feathers to see.
Poultry lice are tiny, flat-bodied, wingless, six-legged, straw-colored insects with broad, round heads. There are several species, and birds can host more than one type of louse at a time. Poultry lice are host specific.
They can’t infest you, farm animals or the family dog. But the bugs can thrive on chickens and other birds, including wild ones.
A typical louse spends its entire life on a single chicken. But lice can move to another host under crowded conditions.
Poultry lice don’t suck blood like the lice found on other species. They feed on skin scales, feathers and scabs. Fall and winter are prime louse times—summertime, not so much.
Chickens should be checked for lice at least twice a month. Spread each chicken’s feathers in her vent, breast, thighs and under her wings. Look for egg clusters or adults at the base of her feathers.
Eggs, called nits, are white and usually found in bunches on lower feather shafts.
Two major types of mites infest chickens: the northern fowl mite and the chicken mite (also called red poultry mites). Scaly leg mites can be problematic, too. Mites are barely visible to the naked eye, if then. They are brown or black or sometimes red after ingesting a blood meal.
Mites are wingless and have eight legs.
Indications of mite infestations include:
- scabbing of skin near the vent
- mite eggs on fluff feathers and along feather shafts
- groups of mites congregating the abdomen, tail, vent or throat
Mites aren’t as host specific as lice and may infest nonavian species.
Northern Fowl Mites
Northern Fowl Mites (Ornithonyssus sylviarum) usually remain on a single bird for life, but they can survive off of a host for two or three weeks. They’re most often a problem during the winter months and spread through chicken-to-chicken contact, though they can also spread between flocks by contact with wild birds or infested clothing and equipment.
Look for this mite during daytime hours. If you use a bright flashlight, these bugs move around on chickens, making them easier to see.
The chicken mite (Dermanyssus gallinae) has a wide range of hosts including several species of wild birds and mammals, including humans. They are night feeders, so it’s important to check for chicken mites after nightfall. After feeding, they hide in cracks and crevices or under clods of dirt or manure, away from light sources, where they mate and lay eggs.
As with the northern fowl mite, eggs hatch in about two days. Larvae molt in one or two days without feeding. So without treatment, chicken mite populations can skyrocket dramatically, causing serious anemia in badly affected flocks.
Young chickens are most susceptible to these nasty little bugs.
Scaly Leg Mites
Scaly leg mites (Knemidokoptes mutans) are responsible for a condition called scaly foot that causes lesions on a chicken’s legs, with dermatitis and thickening of the skin. This mite is microscopic, with an oval body and extremely short legs. It spends its entire life burrowing in the unfeathered, scaled skin of a bird’s shanks and feet.
Older chickens are most commonly affected by these bugs.
The first indication of scaly leg mite infestation is a flaky or powdery look to the bird’s legs, later progressing to lesions or scabs, to lumpy or crusty masses, and finally, deformation of the shank and crippling of the bird.
Unlike other mites, scaly leg mites are easily treated. Simply smear an oil-based preparation such as petroleum jelly to the entire affected area once a day for at least two weeks. This will suffocate the embedded mites. This also softens dead scales that can then be gently scraped or rubbed away.
Treating Lice & Mites
Pesticides for use on poultry are generally available locally at feed-supply stores and from veterinarians. They’re formulated for a specific pest. Something that works for lice may not work for mites and vice versa.
You need to know exactly what you’re treating. If you don’t, consult university publications online or take a sample to your vet. You can discuss treatment protocols with your county extension agent.
If you’d prefer a more natural cure, research at the University of California suggests diatomaceous earth works well to control mites and lice on chickens. Mix it 1 part DE to 4 parts regular sandbox sand in a plastic wading pool as a dust bath, where birds can work the DE into their feathers and onto their skin.
Wear a dust mask. Food-grade DE is safe for birds but can irritate human lungs.
Though their primary host is poultry, sticktight fleas (Echidnophaga gallinacea), also known as hen fleas, infect a wide range of hosts including mammals, even humans. They’re wingless insects with powerful hind legs that can propel them up to 23 times their body length.
They look like but are roughly half the size of the common cat flea.
Sticktight fleas earn their name by embedding their heads in their host’s skin. Find these bugs clustered around the eyes of chickens, or on their combs and wattles. Symptoms can be extreme, with infestation around the eyes leading to swelling and blindness, a decline in egg production, weight loss and death in young birds.
Treatment can be tricky, as the fleas can be difficult to remove. Cotton balls can be used to carefully apply insecticide to areas around the face. This kills the fleas but doesn’t remove them. They must be grasped firmly with tweezers or forceps and pulled out of the skin.
A flea-infested henhouse should be treated with insecticide. But not all insecticides kill sticktight fleas, so consult your veterinarian for viable options.
There are lots of bugs that love to bug chickens, so learn all you can about henhouse pests. Armed with knowledge, you can keep your chickens parasite-free.
Chemical Fly Control
When using chemical insecticides, read and follow the manufacturer’s instructions for safe handling and personal protection. Use appropriate clothing, goggles, gloves, respiratory protection and any other personal protective equipment indicated on the labeling.
To ensure flies don’t become resistant to the pesticides you use, rotate products at least once a year. If you don’t know which insecticides work best in your situation, ask your county extension agent for advice.
Granular fly baits are an effective supplement to sprays but should be used with caution, placed well out of the reach of chickens, wildlife and household pets.
This article originally appeared in the May/June 2022 issue of Chickens magazine.