All Creatures Great and Small


Flies are the fourth largest order of insects and there are over 100,000 species. Most of them are beneficial to some degree as they serve as a food source to many animals and even a few plants. Many breed in organic material such as animal manure and help recycle its nutrients to the soil. Others contribute to the decomposition of dead animals. Flies can also be serious pests. Mosquitoes and other biting flies can cause human deaths by spreading such diseases as malaria, dengue fever, encephalitis, yellow fever and many others. Flies are different from other insects in that they only have a single pair of wings.

You certainly don’t want any flies around schools, day care centers, hospitals, nursing homes, animal shelters or other areas where they can infect people or animals. If you have a fly problem, a good electric flytrap works well but they are expensive. I use an apple cider vinegar trap at our place. I monitor and identify the flies around my home with a simple flytrap. I cut the top off several plastic water bottles; invert the top into the lower portion forming a funnel. I put about two inches of apple cider vinegar in the bottle with a quarter teaspoon of sugar. Almost all flies, no matter what their normal food preference, will enter the trap. I then pour them out through a sieve, let them dry and identify them. Gallon size milk jugs cut as described above and baited with apple cider vinegar and sugar will catch a lot of flies in a large building or yard.

House flies (Muscidae – Musca domestica)

House flies have a gray thorax (part where head is connected and wings are attached) with four dark stripes, and a mottled abdomen (posterior portion). These flies are considered “filth flies” and will feed on excrement, garbage, carcasses, and even human secretions from wounds and mucous membranes. If you accidentally eat the larvae (maggots) in contaminated food, they can survive in your intestine. They can harbor over 100 different pathogenic organisms and are capable of transmitting more than 65 diseases and bacteria that can cause duodenal and stomach ulcers. House flies are the most common fly in the world that is found around homes and areas with livestock.

When you swat a fly remember that is has an unblurred range of vision of only abut 1½ feet. You should aim your flyswatter about 1½” behind the fly, because when houseflies take of from a horizontal surface, they jump upward and backward. Set out a saucer filled with bubble soap to attract and kill flies. Adult flies eat only sugar, so make some light Karo Syrup or honey or sugar water with 5% boric acid or borax baits.

I have frequently written about hanging Ziploc bags filled with water around doors and windows. The sun’s refractive light is said to disorient flies when the sun’s rays are shining through the bags and the flies won’t come in the building. From the mail I have received, these bags work very well.

Little house flies (Fannidae – Fannia canicularia)

Little house flies are dull gray with yellow on the upper abdomen and 3 dark longitudinal stripes on the top of the thorax.

These flies resemble house flies but they fly in circles in the middle of a room or on a porch and don’t appear to land. They can lay their eggs in any organic material including compost piles, pet feces, dead leaves, etc. They have been known to enter the urinary tract of naked sleeping persons and causing urinary myiasis. To prevent these flies from appearing, empty and clean all food handling equipment, dishes and garbage containers and daily remove and/or bury all animal droppings, fruit and organic debris inside and/or outside. They do like beer so you can put two packets of aspartame in 2”of beer in an open container to act as a bait for these flies. You can also use a fly swatter with a sticky side to swat them when they are circling.

Cluster flies (Calliphoridae – Pollenia rudis)

Cluster flies are about ½ up to ¾ of an inch in size. Slightly larger than the common house flies, they move indoors in the winter in hundreds or even thousands of individuals, hence the name. Unlike house flies, cluster flies are not associated with poor hygiene and poor sanitary conditions. These flies do not carry diseases and other hazards that may affect humans because they do not lay their eggs in human food. They parasitize earthworms in the ground outside. When they invade homes for the winter, they will infest attics, basements, unused rooms, wall voids, ceiling voids and garages.

The best way to deal with cluster flies is to prevent them from coming in. Here are some tips: Check all the obvious entry points. Check your windows and doors for small openings. Cluster flies can squeeze through the sides of doors and windows, so make sure there isn’t enough space for them to pass through. Seal or patch cracks and crevices. If you use a screen, make sure there aren’t any holes that the insect can go through. Check your cellar door for possible openings too. These are possible entry points because your basement is an ideal undisturbed spot that cluster flies choose to hibernate in. If you have an attic, do the same. Basically, any room or area in your home that is not visited much by any of the people in your home are the ones you should check.

Blow flies (Calliphoridae –Phormia, Phaenicia,Cynomya & Calliphora)

Blow flies are larger than house flies and are normally shiny green, blue, bronze or black in color.  Blow flies feed on decaying animal matter and if you have them in your house it is an indication of a dead animal in the wall or ceiling. Occasionally the only sign of these flies in an early infestation is when the larvae fall from the ceiling void onto the floor. If you can find and remove the carcass of the dead animal they are feeding on, it will speed up the process of them leaving. If you can’t, there isn’t much you can do except be patient and wait for the dead animal to dry up. They can also lay their eggs in dog feces or any animal matter with a high protein content, including dry cat food. Common names for the most frequently encountered blow flies are black blow flies, greenbottle flies and bluebottle flies. Greenbottle and bluebottle flies are metallic green or blue in color. Black blow flies have a black sheen. These flies are also used by forensic entomologists to establish the time of death in human fatalities.

Flesh flies (Sarcophagidae)

Flesh flies resemble house flies but differ in only having three stripes on a gray thorax. Some species lay their eggs in foul smelling dead animal matter while others will lay their eggs in open wounds on horses, cattle and other animals. There was a case in Albuquerque several years ago where these flies laid their eggs in the festering wound of a person in a nursing home. One species can lay their eggs in the noses or eyes of humans causing myiasis, which can be serious. Proper sanitation and exclusion is the best way of controlling flesh flies.

Fruit flies (Drosophilidae)

Fruit flies are usually found in the kitchen where they feed and breed on food spilled in out of the way places such as behind or under appliances or similar areas. These small flies have distinctive red eyes, which you can see with a hand lens. They are tan or brown in color and about 1/8” long. They are also known as pomace flies and vinegar flies. They can be serious pests when found in food handling establishments as they breed in and feed on fruits, vegetables and any moist, decaying organic material. They have been known to cause intestinal problems and diarrhea when fruit containing their larvae are eaten. They will also breed in discarded fruit juice and soft drink cans and in unsecured bottles of wine. They are also very prolific as the female can lay about 500 eggs which will hatch and reach adulthood in as little as eight days.

These little flies are also beneficial as they have been studied in research in genetics. This research became the foundation on which future genetic research was built. The species Drosophila melanogaster is the one used in genetic and heredity studies. It is also a very common fly in many homes and businesses.

In your home you can control fruit flies by totally eliminating all breeding material. They are attracted to acetic acid (vinegar), so put some drops on duct tape or glue boards. Or you can just fill a small paper cup with vinegar and the flies will dive in.

Hump-backed flies (Phoridae)

Phorids are small flies, about an 1/8” long and tan to dark brown in color. They have a distinct hump-backed shape thorax, hence their common name. They do not have red eyes as fruit flies do. When these flies are disturbed, they will run along the surface they are on rather than flying away.

These flies breed in any moist organic material including dirty mops, garbage, decaying fruits and vegetables and dead animal matter. They are also known as coffin flies because of their presence where dead bodies are found, including inside of coffins. There are over 220 species of phorid flies in the United States.

You have to eliminate the food source and breeding areas in order to control them in your home or business.

Dung flies (Sphaeroceridae)

Sphaerocerid flies are sometimes called dung flies, but that name probably isn’t appropriate. While they will breed in dung, they will also breed in other organic materials and are often found in areas where phorid or drosophilid flies breed. Sphaerocerids can be recognized by the enlarged size of the first tarsal segment on their hind legs. The tarsi are the last five segments on the leg. They are very small, about an 1/8 of an inch and dark-colored. There are over 240 species of sphaerocerids in the United States and they are easily transported around the country as they will frequently breed in decaying material carried in commerce between states.

These flies will breed in organic material spilled in cracks in the floor, unclean trash containers and even the bottom of elevator shafts if it is damp and has decaying organic matter there. They can be a problem in food establishments if there is a lot of spilled food that works its way into floor cracks or expansion joints. The best way to control these flies is to find our where they are breeding and totally eliminate the decaying material from the area.

Moth flies (Psychodidae)

Moth flies are small flies with hairy wings that resemble small moths. They are also called filter flies and drain flies. They are usually found in the bathroom. They will breed in the gunk buildup in drains and will often be found in the tub, on shower curtains or the wall. They are poor fliers and seem to just hop around. The larvae live in gelatinous material in sink and floor drain traps, in sewer treatment plants and in septic tanks. They will also breed in damp crawl spaces under a house. In a commercial building you can put duct tape sticky side down on drains to see which ones they are breeding in. You need to keep your drains clean to control these flies as they have a very short life cycle. They can go from egg to adult in a little over a week in some areas.

Fungus Gnats (Sciaridae)

Fungus gnats are very small flies with long legs and long antennae and distinctly patterned wings. They are dark brown or black in color. They are generally found in over-watered house plants where the larvae feed on fungus in the potting soil and moist organic material. The best way to control them is to let the plants dry out almost to the point of wilting before re-watering. That will kill the larvae in the soil. Then put an inch of aquarium gravel on the soil to prevent female fungus gnats from laying anymore eggs in the potting soil. You can also place a yellow sticky trap on a stick in the soil to catch the adult gnats.

Mosquitoes (Culicidae)

Mosquitoes are small, slender, biting flies. They have a long, thin mouth part designed for piercing the skin and sucking out blood. They require water to lay their eggs. They are very important disease vectors and can transmit West Nile Virus, Encephalitis and other diseases in the United States. If you have mosquitoes, make sure you wear a good non-DEET mosquito repellent when you go outside. Never use the DEET products that government agencies recommend as DEET (N,N-diethyl-m-toluamine) is a chemical that some people have severe reactions to. It is a fact that DEET works well as long as it is full strength. However, when it begins to weaken, it actually attracts mosquitoes and you have to put more on, which means absorbing more of the chemicals into your system. Most non-DEET products (catnip, citronella, and lemongrass) are effective for two or three hours before having to be reapplied, but they do not contain potentially dangerous chemicals.

Remove all standing or stagnant water if at all possible. This means old tires, barrels, cans, wading pools that aren’t being used, bird baths and other items that can hold water. You can apply a light coating of food-grade diatomaceous earth on any water that can’t be removed. Eucalyptus oils, garlic extracts and extracts of orange and lemon peels will kill mosquito larvae in the water.

If you have adult mosquitoes in your grass or bushes, you can spray them with Greenbug for Outdoors. Catnip is a very good repellent according to a report from Iowa State University. Other good repellents include lemongrass, basil, birch, mint, rosemary, spearmint and yarrow. Geraniums or basil plants planted near your doors will repel mosquitoes. Citronella and pennyroyal both work but have side affects. Pennyroyal may increase the risk of a miscarriage if you are pregnant and citronella has been known to attract female black bears. Test anything you put on your skin on a small portion first to make sure you aren’t allergic to it. Again, never use repellents that contain DEET.


About askthebugman

I have been in the pest management industry for over 40 years. In that time I have used almost every pesticide available to control so-called “pests”. With this experience, I have learned over the years that the pesticides we use are far more dangerous than the pests we are trying to control. As a result, it has become a passion for me to improve the quality of life for humans and the planet, by assisting people to not only become more educated and aware of their environment – but also by learning to manage their home and business with a sustainable and healthier approach to tending to unwanted infestations of bugs. Please enjoy my blog posts, check out my publications, utilize my services, or simply stay in touch if you have a bug question…


One thought on “Flies

  1. I suddenly have 1/2 inch long typical looking maggots on my bathroom floor and a few in the shower. I thought that they were dropping from a break in the dropped ceiling but they appear to be emerging from the shower drain. I poured some straight bleach in the drain and a few minutes later had several more in the shower. I repeated the bleach and covered the drain with plastic wrap and set the bleach bottle on top of that last night. This morning I only found 2 maggots on the bathroom floor. I have seen some blue bottle flies near the garbage can but that is a good 25 feet away from my 1st floor apartment and it is covered. I haven’t seen any flies inside the apartment. Could these be bottle fly larvae? How do I get rid of them (whatever they are)?
    Your help would be most appreciated! Thank you!

    Posted by Tamara Morgan | June 11, 2016, 10:51 am

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Enter your email address to follow this blog and receive notifications of new posts by email.

Join 173 other followers

%d bloggers like this: