University of Maryland Extension


life stages of a fly
House fly life cycle

House flies 

The most common fly found in and around homes. The adults are about 1/4 inch long and dull gray. The larvae or maggots are 1/4 to 3/8 of an inch long when mature. They are whitish, eyeless, legless and taper towards the front. Food varies from excrement to human food. Adults feed only on liquid food and can mechanically transmit many disease pathogens. Female flies will seek out any warm, moist material that has sufficient food for larval development.


To control house flies, locate larval breeding sites and eliminate them. This includes timely removal of trash and keeping garbage cans as dry and clean as possible. Use cans with tight fitting lids. To prevent adults from entering homes, tighten screens, windows and doors. Seal all holes and entry points. Make sure all vents are tightly screened. Adult flies can be trapped with baited fly traps or sticky fly tape. Spraying is generally not effective inside the home. 

Blow Flies, Greenbottle, and Bluebottle Flies

blow fly. Mike Raupp

close up green bottle fly

blue bottle fly

Blow fly

Green bottle fly

Blue bottle fly

Blow flies and Bottle flies are similar in size to house flies, but are metallic blue or green. These flies may breed in dead animals, feces and/or garbage depending on the species. If a large number of these flies are found in the house, they are usually breeding in the home or in the immediate area. Examples of breeding sites may be a dead mouse or squirrel in the attic, or a dead bird in the chimney. The green bottle flies may be commonly seen on pet feces outdoors.


The life cycle is very short (2-4 weeks). So, as with the house flies, it is important to locate and eliminate the larval breeding site. This may involve timely removal of pet waste from the yard, locating a dead animal or cleaning up garbage cans. Adult control is the same as for house flies.

Additional Resource

Publication: (PDF) HG 26 Flies in and Around the Home

Maintained by the IET Department of the College of Agriculture and Natural Resources. © 2019. Web Accessibility