Flies

The common name from the Bottle fly comes from "bot" which is an old term for maggot.  These flies are more than just a nuisance, they are of medical importance because of their mechanical transmission of disease organisms and ability to cause myiasis in humans and animals.

Adults are about 1/8-5/8" long.  Color partly or wholly metallic blue, green or dull brassy, sometimes black.

Mature larvae are about  3/8 - 7/8" long: eyeless, legless, and tapering towards head from large rounded rear segment.  Color is pale yellow to white.

Females lay their eggs on suitable larval food material.  Upon hatching, the larvae may feed on the surface and then burrow into the food material which is less decayed.

Blow fly disease carrying possibilities are often overlooked.  Because many species feed on filth such as human excrement and sewage and/or develop in carcasses of infected animals, these flies may easily infect the food humans eat. 

Most species develop in meat or animal carcasses, but if these are not available they will use animal excrement, decaying vegetation, and/or garbage.

They are good fliers and are most active on sunny days, and primarily rest on cool and/or cloudy days.  Inside they are attracted to the bright light coming through windows.

The common name for the Cluster fly reflects this species habit of forming compact clusters of hibernating  individuals, typically in wall voids or attics.

Adults are about 3/8" long, robust and dark gray in color, non-metallic.  They have sluggish movements, with a buckwheat honey odor when crushed.

Adults overwinter in sheltered places, emerging in the spring to mate.  Eggs are laid in soil cracks and hatch in about 3 days.

As days shorten and the weather cools, cluster flies often enter structures to overwinter, sometimes traveling more than a mile to do so.  They usually occupy attics and/or the between-wall voids of walls which receive the most sunlight.  Typically they use the same structure year after year.  They do not multiply within structures.

Once stimulated cluster flies seek light.  Cluster flies can usually be found at windows crawling on the panes or frames or around lamps or lights.  They are sluggish in their movements in comparison to the house flies. 

The common name of the Face fly comes from the adult habit of feeding the mucus and watery secretions found around the eyes, nostrils, and mouths of cattle.  They are a nuisance pest in structures where their behavior resembles that of cluster flies, coming in to overwinter and being active on warm day.

Adults are about 1/4" long.  They are dull gray in color. 

Mature larva are about 1/4"-7/16" long: eyeless, legless and tapering towards head from large rounded rear segment.  Their color is yellowish.

Females lay their eggs (30-230) only in fresh undisturbed cow droppings. 

Face flies are present outside from April to October, with numbers building towards Autumn.  Females feed on the mucus and watery secretions of cattle and horses faces.  They also feed on the blood coming from wounds made by biting flies and on dung fluids.  Males feed primarily on flower nectar.

Adults seek sheltered locations in which  to overwinter beginning in late August or September.  Such places include attics, wall voids, and basements of structures.  They tend to use the same structure year after year.

Once stimulated face flies seek light.  Face flies can usually be found at windows crawling on the panes or frames or around lamps or lights.  They are sluggish in their movements in comparison to the house flies. 

The common name of Flesh fly comes from the fact that the larvae of most species develop in spoiling meat and decayed flesh.  There are about 327 species of flesh flies in the United States and Canada.

Adults usually are about  1/4 - 7/16" long.  They are relatively large, robust flies.  They are a dull blackish gray.  The thorax usually has 3 black longitudinal stripes.  Abdomen often with checkerboard pattern of black and gray spots, but sometimes striped, banded, or spotted, whose markings usually shift from dark to pale depending on the viewing angle.  Tip of abdomen usually red or pink.

Mature larvae are about 3/8 - 3/4" long, eyeless and tapered towards head from large rounded rear segment.  Head is represented by a pair of dark hooks.  Their color is white or pale yellowish.

Females give birth to larvae/maggots instead of laying eggs.  The larvae are laid on the larval food material.  Many species develop in excrement or decaying flesh, in garbage or a variety of materials, which makes them a human health concern.

Adults are typically found outside of flowers or on larval food materials, and animals that they parasitize such as insect, snails, and other invertebrates, turtles, humans and other mammals.  

Mature larvae usually leave  the breeding source in  search of a drier place in which to pupate.  Hence, occasionally mature larvae/maggots can be found crawling about inside a structure.

The common name of Fruit fly comes from their small size and fondness for fruits as egg laying development sites. 

Adults are about 1/8" long.  They are dull, tan to brownish yellow or brownish black in color.  Eyes are usually bright red. 

Mature larvae are about  1/4 - 3/8" long, eyeless, legless and tapered toward the head.  Head is represented by 2 dark hooks.  They are near white in color except for the mouth hooks which are black and breathing pores which are yellowish in color.

Adult females lay their eggs near the surface of fermenting fruits and vegetables or near the cover crack of imperfectly sealed containers of such materials.  The larvae develop in the briny or vinegar like liquids of the fermenting materials where they feed near the surface and primarily on yeast, for about 5 - 6 days.

Small fruit flies are attracted primarily to fresh fruit and vegetables and those fermenting because of yeast.  Material commonly infested include bananas, grapes, peaches, pineapples, tomatoes, mustard pickles, potatoes, etc. and fermenting liquids such as beer, cider, vinegar, and wine.

Adults tend to hover in small circles.  Because of their small size, many species are able to penetrate ordinary screens.

These flies receive the common name of the House fly from being the most common fly found in and around homes.  It is not only a nuisance pest but of greater concern is its potential as a carrier of disease organisms, having been found to harbor over 100 different pathogenic organisms.

Adults are about 1/8 - 1/4" long, with female usually larger than male.  Their color is dull gray, face with 2 velvety stripes, each silver above and gold below.

Mature larvae are about 1/4 - 3/8" long; eyeless, legless, and tapering towards head from large rounded rear segment, head represented by a pair of dark hooks.  Their color is cream but with greasy appearance.

The adult female lays her eggs singly but in clusters of 20 -50.  She will lay a total of 350 - 900 eggs in her lifetime.  Eggs are laid in most materials and hatch in about 8 - 20 hours.

House flies are general feeders, being attracted to a wide variety of substances from excrement to human foods.  Through regurgitation they are able to liquefy most desirable solid foods so they can feed on them. A house fly excretes and regurgitates whenever it comes to rest.  This habit coupled with its many body hairs and bristles and the sticky pads at the base of the claws on each leg make house flies well adapted for transporting disease organisms.

House flies have been shown to harbor over 100 different kinds of disease causing pathogens, many of which are associated with filth.

During the day, house flies tend to rest less than 5 feet from the ground on walls, floors, and various objects.  At night they rest primarily above 5 feet on ceilings, walls, electric wires, dangling light cords, corners of buildings, plants, etc.  Their night resting places are usually near their daytime food sources.

(Insect Information excerpted from the NPCA Field Guide to Structural Pests)