Fly Identification & Characteristics

Blow Fly Identification

Origin

Several species that are native to North America, and widely spread throughout the continent and into Latin America.

Biology

The blow flies are important decomposers of dead animals and other rotting organic material, such as decomposing plant material. They are the first insects to arrive at a newly deceased carcass and their larvae are frequently used in forensic science to determine facts about a crime scene. The maggots also have been used in “maggot therapy”, to eat dead tissue off the skin of victims of burns or wounds. Females may lay several hundred eggs on an appropriate larval food source, with development to the adult stage being completed in about one week in hot, humid conditions. The larvae leave the food and may squirm long distances to find a protected crevice in which to pupate, often falling through ceilings or across floors because of this.

Identification

In general the blow flies are shiny and metallic, with species ranging from green to bright blue to a coppery orange to almost black, and species names are assigned accordingly. The adults are from 10 to 15 mm long and robust, with compact, wide bodies. They are loud, buzzing fliers and are strongly attracted to lights. The larvae are the typical legless, white maggots of the filth flies, with the head end noticeably tapering to a point and the posterior much wider and flattened from behind. Identification to species is done based on the specific patterns of the lines of the spiracles, found at the posterior end.

Characteristics Important in Control

Control of the source of the larvae is critical, involving cleanup and proper maintenance of garbage containers, removal of dead rodents or birds, and elimination of piles of yard debris or animal feces outdoors. Adult entry to structures is prevented by good building maintenance. The use of UV light traps is highly effective in trapping adults, along with bait granules or bait strips, and possible use of residual insecticides on surfaces the adults frequent.

Cluster Fly Identification

Origin

Possibly native to North America, and found throughout the United States, Canada, and in Europe.

Biology

The pest significance of the Cluster fly is due to the habit of the adults gathering in large numbers within structures, where they spend the winter months. On warm winter days they may awaken and become a nuisance within the structure. They are large flies and poor fliers, and may land on arms or faces as they move about. Once spring warmth activates all the flies they emerge from the structure in great numbers to gather on walls, furnishings, or objects outdoors. When crushed they give off an unusual, sweet odor. The larvae are parasites of earthworms. The female lays eggs in the soil and the maggots seek out earthworms, which they penetrate and live within, eventually killing the worm. The life cycle from egg to adult takes about one month or a little longer.

Identification

The adult flies are unusual for their family, in that most other species of Calliphoridae are shiny and brightly colored. The Cluster fly is a dull, dark gray color, it is slightly larger than the House Fly and without the dorsal stripes on the thorax, and the thorax of the Cluster fly is covered with short, curled, yellow hairs. When at rest the fly holds its wings flat over the abdomen with the tips crossed.

Characteristics Important in Control

Control of the larval stage is not possible, so attention instead is given to either preventing the entry of the adults into structures, or killing them once they are hidden in voids. Closing off the small openings that allow entry is good long-term prevention, and treating enclosed voids with a dust insecticide will effectively kill the adults. If the flies are resting in large accessible voids, such as an attic, they may be captured with specialized UV light traps.

Drain Fly Identification

Origin

A number of native species of flies in this family occur throughout North America.

Biology

The genus Phlebotomus contains some species which are blood feeders, and they are vectors of several important diseases including Leishmaniasis. The larvae of this family of flies feed on organic material they find in damp situations, including on soils or leaf litter. In structures this may be a sludge buildup in floor or sink drains, giving the flies’ one of their common names. They may also occur in large numbers in septic systems, sewage treatment plants, or dirty garbage containers. The eggs are laid in masses of from 30 to 100 eggs, on the surface of the material in which the larvae will feed. The larvae feed within the sludge, breathing through siphon tubes on their body that project out of the material. The time from egg to adult fly may be from 8 to 24 days, depending on the temperature. Adult flies are attracted to lights.

Identification

The adult flies are very small, and covered with short, gray hairs on their wings and entire body. The wings are oval and held flat over the abdomen, at a slight outward, or “delta”, angle.

Characteristics Important in Control

Elimination of larval breeding sources is critical, by removing sludge buildup in floor or sink drains and controlling moisture accumulation in low spots on floors or exterior areas. Regular washing of dumpsters will remove spilled materials.

Fungus Gnats

Origin

Many species of these tiny flies are native to North America.

Biology

Fungus gnats get their name due to the food of the larvae, which feed on molds and fungi found in damp locations. They commonly are found in homes due to moisture sources in potted plants, under appliances, in crawl spaces or beneath slabs, in moisture problems within walls, or from damp locations in exterior landscape. In mushroom farms their numbers can be explosive. Some species also feed on the roots of plants, while others may feed within plant tissue as leaf-miners. On occasion the small larvae may migrate from the feeding source in long, snake-like masses, moving to a drier location to pupate. The length of time from egg to adult may be less than 2 weeks, depending on the temperature.

Identification

The sciarid fungus gnats are tiny flies, only 2 to 3 mm long. They are brown to black and have long, thin, pointed abdomens.

Characteristics Important in Control

Control of sources of moisture, and the resulting fungi or decaying organic material, is the key to the control of fungus gnats. They are drawn to lights as adults, but light traps and residual sprays will not affect the larvae that are hidden in a protected, damp environment.

House Fly Identification

Origin

This species is found abundantly throughout the world, and in many countries, where sanitation is not adequate and human wastes are commonly deposited outdoors, the House Fly is responsible for the spread of numerous serious diseases. Included in this list are dysentery, typhoid, cholera, poliomyelitis, yaws, anthrax, tularemia, intestinal parasites and eye parasites. It is incriminated in the spread of food infections from bacteria such as Shigella and Salmonella.

Biology

The House Fly got its name from its common occurrence in homes, particularly during more rural times when horses and livestock were common around homes, and used as transportation. It breeds prolifically, with females laying from 350 to 900 eggs in their lifetime, with a record of 2,400 eggs from a single female fly. The interval from egg to adult fly can be completed in less than one week under warm, moist conditions, and there can be many generations each year. Adult flies live as long as 54 days and females mate multiple times. Breeding sites for the larvae will be any moist, decomposing organic material, such as piled lawn clippings, animal waste, filthy garbage containers, outhouse receptacles, and decomposing plant materials. The larvae commonly leave their food source to seek a drier location in which to pupate, migrating as much as 150 feet away, and thus appearing on floors or countertops they may fall or crawl onto.

Identification

The adult fly is only about 5 or 6 mm long, and is most easily distinguished by the pattern of wing veins, the 4 dark longitudinal stripes on the top of the thorax, and the yellow sides of the abdomen on the males. On the wing there is a distinct 90 degree upward bend of the middle vein as it nears the outer end. The larvae are a typical white, legless maggot, and the pattern of the lines of their spiracles, at the anal end, will be a distinctive characteristic for the species. The pupa is brown and egg-shaped, without any seams, and the emerging fly uses a pumping device called a ptilinum to force its way out of the pupa.

Characteristics Important in Control

Sanitation and removal of any and all potential breeding sites is crucial. Cleaning surfaces of spills and keeping foods covered and stored properly will reduce the attraction of flies and the potential for contamination of the food. The adults are attracted to lights, and the use of UV light traps will be very effective indoors. Fly bait granules or strips can be highly effective in killing adult flies outdoors, and treating surfaces the adults land on with a residual insecticide can also reduce their numbers. Other kinds of fly traps such as sticky boards and tubes or jars and bags that are baited will be effective as well.

Phorid Fly Identification

Origin

These flies, including the common species found in the United States, may be found throughout the world.

Biology

Phorid flies breed in many of the same conditions that support either vinegar flies (fermenting vegetable and fruit juices and material) or drain flies (accumulations of wet organic sludge). They may also live in fungus or decaying plant tissues. Their name of “hump-backed” fly is derived from their appearance, in which their thorax is prominently arched on top. Adults are attracted to light, and have the distinctive habit of running quickly across a surface when they land on it. A few species of Phoridae are parasites of ants, and are being studied with respect to possible bio-control efforts for Red Imported Fire Ants. Some species also have been found invading wounds in the skin of humans, and cases of myiasis (flies within human digestive tracts) are most common with these flies.

Identification

The common structural-invading phorids are very small flies, only about 3 mm long. They strongly resemble the common vinegar flies, but differ by not having red eyes or the banded abdomens. Their color is an orange-brown, they have relatively long legs, and the profile of the thorax shows it to have a raised or “humped” appearance. Adults also have the characteristic habit of running quickly on surfaces.

Characteristics Important in Control

Elimination of the source of the larvae is critical, and emergence of new adult flies will continue until this source is eliminated. Any buildup of organic matter in cracks or floor drains can support larvae, along with unwashed garbage containers, spilled juices, or over-ripe fruits and vegetables. Production of large numbers of these flies may be associated with broken plumbing beneath concrete slabs or within walls.

If you have a fly problem and would like to have a Craig Thomas Pest Control, in partnership with Orkin Pest Control, representative speak to you, give us a call! Contact us by phone 800-255-6777, email for your free inspection today!

We at Craig Thomas Pest Control, Inc. are grateful to Univar Profession Products and Services for pest information incorporated into this work.

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