Pest ID: Blow Fly
Calliphora spp., Phaenicia spp.
Adults measure about 1/8″ – 5/8″ (4 – 16 mm) long. Color partly or wholly metallic blue, green, or dull brassy, sometimes black. Referred to at times as Black Blow Fly or Green Blow Fly. Mature larva about 3/8″ to 7/8″ (9 – 22 mm) long; eyeless, legless, and tapering towards head from large rounded rear segment. Color pale yellow to white. You can see the adult Blow Fly picture showing the detail and common color.
Places Most Commonly Found:
Females lay their eggs (up to 2,373) on suitable larval food material. Upon hatching, the larvae may feed on the surface the burrow into the food material which is less decayed. Mature larvae will usually leave their food material to pupate. These flies feed on filth such as garbage, excrement, sewage, and/or develop in the carcasses of dead animals. Dead birds, rodents and other small animals are the primary sources of breeding areas. Often called Blow Fly Maggots, these flies are usually the first insects to arrive and infest after an animal dies. Their larvae are often used by forensic entomologists to help determine the time of death in murder cases. The list of diseases associated with Blow flies is numerous including several intestinal track problems such as E. coli and cholera.
Most Active Period:
Some species are strong fliers and have been known to fly 4 – 28 miles from their point of origin. The are most active on warm, sunny days,, and primarily rest on cool and/or cloudy days. Inside they are attracted to the bright light coming through windows. Eggs hatch between 59 F (15 C) to 109 F (43 C). Development time in the south is usually 7 to 20 days. Optimum temperature for activity and development is 72 F (22 C).
Difficulty of Control:
A Blow Fly infestation is difficult to control without addressing sanitation issues. Moderate to easy to control when sanitation issues are addressed along with exclusion and use of pesticides in or near breeding areas.