Blow Fly Control

Blow Flies are the large iridescent metallic flies people often call "bluebottle" or "greenbottle" flies. They are the primary insect colonizers of carrion (dead animals), arriving within minutes of death to lay eggs that develop rapidly into maggots that consume the carcass. In nature, this is an ecologically beneficial role — Blow Flies are major decomposers and forensic entomologists use the timing of their colonization to estimate time of death in criminal investigations. In Metro Atlanta homes, however, the presence of Blow Flies indoors almost always signals a dead animal somewhere in or under the structure.

The most common scenarios: a rodent (mouse, rat, squirrel) died in a wall void or attic after bait treatment or natural causes; a bird died in an attic, chimney, or behind exterior siding; a bat died in an attic; an opossum or raccoon died in a crawl space; or roadkill near the property is producing flies that enter through gaps. Multiple Blow Flies in a structure are essentially diagnostic — there is a carcass somewhere. Servitix Blow Fly service prioritizes locating and removing the carrion source, which is the only way to eliminate the infestation.

Adult Blow Flies are 3/8 to 1/2 inch (10 to 14 mm) long with stout, robust bodies in metallic blue, green, copper, or bronze coloration with an iridescent sheen — significantly larger and more brightly colored than House Flies. The body is covered in stiff bristles, the head bears large reddish compound eyes, and wings are clear with prominent veins. The most common species in Metro Atlanta are the Common Bluebottle Fly (Calliphora vicina), Green Bottle Fly (Lucilia sericata), and Black Blow Fly (Phormia regina) — all in the family Calliphoridae and all sharing the metallic iridescent appearance.

Larvae (maggots) are creamy-white to yellowish, segmented, tapered cylindrical grubs that grow to about 3/4 inch when full-grown. They are typically found within or adjacent to the carcass. Adults are loud and clumsy fliers compared to House Flies, often heard buzzing against windows as they try to exit a structure after emerging from a hidden carcass. The combination of large size, metallic iridescence, indoor presence, and clumsy flight is diagnostic. The classic scenario is the homeowner finding multiple metallic flies on windowsills inside a room with no obvious food source — the dead animal is in a wall or ceiling void above or beside the room.

Blow Flies are masters of carrion detection. Adults can locate a dead animal from over a mile away by detecting volatile decomposition compounds (cadaverine, putrescine, sulfur compounds). Females arrive within minutes to hours of death and lay 100 to 300 eggs in clusters near the body openings (mouth, nose, eyes, wounds). Eggs hatch within 8 to 24 hours into maggots that feed continuously on the carrion. Larvae develop through 3 instars over 5 to 14 days, then leave the carcass to pupate in nearby soil, debris, or wall void material. Adults emerge 6 to 14 days later, depending on temperature.

The full life cycle from egg-laid-on-carcass to emerged-adult takes 2 to 4 weeks at warm temperatures. This is significant because it explains the typical homeowner experience: a rodent dies in a wall on day 0, decomposes for 3 to 5 days while Blow Flies lay eggs, maggots feed for 1 to 2 weeks (often producing the worst odor period during this time), pupate inside the wall void for another week, then adults emerge en masse — sometimes 50 to 200 at once — startling the homeowner who thought the odor problem was finally fading. After emergence, adults hunt for windows to exit (which is why you see them on windowsills).

The infestation source is always a carrion item. In Metro Atlanta home infestations, the most common sources are: rodents (mice, rats, squirrels) that died in attics, wall voids, or crawl spaces after consuming bait or from natural causes; birds that died in attics, chimneys, or behind exterior siding (window-strike victims sometimes get trapped and die in wall voids); bats in attics (especially after bat exclusion work if a bat got stuck); opossums or raccoons in crawl spaces or under decks; squirrels in chimneys or attics; pet rodents or reptile feed (sometimes mice escape, die, and are not located); and roadkill animals near a structure or in a window well.

Outdoor carcass sources can also produce indoor Blow Fly populations if the carcass is close enough to the structure — adults will follow food odors into homes through gaps. Compost piles containing meat scraps, improperly-sealed pet waste, dead pets that have been buried close to the foundation, and outdoor garbage with meat residue all attract Blow Flies that may then enter structures. Adults rest on shaded exterior walls, under eaves, on dumpster pads, and in shady vegetation between feedings. Commercial food-service environments handling meat are major Blow Fly sources, and butcher shops, processors, and any facility with significant meat waste need ongoing fly management.

Blow Flies are significant mechanical disease vectors. They feed on carrion, animal waste, and decaying organic matter — picking up pathogens including Salmonella, E. coli, Shigella, Campylobacter, and various parasitic protozoa and helminth eggs — then land on human food, food-prep surfaces, dishes, and drinking water. Their habit of regurgitating digestive saliva onto food (the same feeding mechanism as House Flies) is the actual transmission pathway. They are documented vectors of foodborne illness and are sometimes associated with myiasis (the infestation of living tissue by fly larvae), particularly in healthcare and elder-care settings.

The presence of Blow Flies indoors is also a health concern through what it indicates: a decomposing animal carcass somewhere in the structure. Decomposing animals produce odors and aerosolized particles that can trigger respiratory issues in sensitive individuals, expose family members to zoonotic pathogens, and attract secondary pests including carpet beetles, dermestid beetles, and other pests that feed on dried animal remains after the wet decomposition phase ends. The longer a carcass remains in a structure, the more secondary pest issues develop. Locating and removing the carcass is therefore both an immediate odor remediation step and a longer-term pest-management need.

Servitix Blow Fly service is primarily a carcass-location and removal operation. Our technicians inspect attics, crawl spaces, wall voids (accessible through outlets and switch plates), chimneys, and any space where an animal could have died and been hidden from view. We follow odor cues, fly clusters, and visible exit points to narrow the location. Once the carcass is located, it is removed (sometimes requiring opening drywall or accessing crawl space ductwork), the area is cleaned and deodorized with enzymatic treatment, and any remaining maggots or pupae in the vicinity are treated. Adult flies in the living space are knocked down with targeted aerosol or trapped with sticky window strips.

Prevention focuses on exclusion to keep wildlife and rodents from entering structures in the first place. Seal gaps around utility penetrations, install or repair attic vent screens and ridge-vent gap covers, screen chimney caps, repair damaged exterior siding, seal foundation cracks, and address rodent exclusion. If rodent bait is being used in the structure, place it where any dying rodents will be accessible for removal rather than dying in inaccessible wall voids — or use snap traps and live traps instead of bait. Address outdoor carrion attractants by promptly disposing of dead animals in sealed bags, securing pet waste, and managing compost piles to exclude meat scraps. Our maintenance plans include wildlife exclusion inspection and rodent monitoring to prevent the carcass-in-wall scenario.