Size
Adults are 1/4 inch to 3/8 inch long with compact, wide bodies.
Color
Blow flies are usually shiny and metallic ranging from bright blue to coppery orange to almost black.
Habits
Blow flies are extremely common. They are loud buzzing fliers that are attracted to lights, food odors and warm/cool currents around windows and doors. The sudden appearance of dozens of blow flies in a building could indicate there is a dead rodent, bird, or other animal in the wall, ceiling or attic.
Diet
Blow flies are scavengers that feed on trash, decaying animals and animal feces. They are usually the first insect to reach a dead animal. Blow flies are an important part of the decomposition process because they recycle nutrients back into the soil.
Reproduction
Female blow flies lay several hundred eggs on or near suitable food sources such as garbage containers, dumpsters and compost piles. Tiny maggots hatch from eggs in 6 to 48 hours then undergo several stages before becoming adult flies. It takes 16 to 35 days for the development from egg to adult.
Other Information
Maggots have hook-like mouthparts that tease apart tissues in which they live. Adults have sponge-like mouthparts similar to those of house flies. Blow flies are important decomposers of dead animals and other rotting organic material, such as decomposing plant material. Their larvae are frequently used in forensic science to determine facts about a crime scene.
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. The use of UV light traps, such as the Fly Relief Fly Trap is highly effective in trapping adults, as are bait granules or bait strips such as Maxforce Fly Granules and Stimukil Fly Bait.