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Phorid Flies


Adults are about 1/64-1/4” long with a humpbacked appearance in lateral view. Phorid flies can be yellowish, black or brown in colour. Short antenna, basal 2 segments very small, 3rd segment globular with a long bristle. Wings have strong, heavily pigmented veins in front area, remaining veins weak and without crossveins. Larvae up to 3/8”; spindle shaped with projections on rear segments to shorter, broader projections dorsally. Colour is whitish, yellowish white or grayish.

Females lay their eggs either onto or into the larval food, with 1-100 being laid at one time and up to 749 in her lifetime. There are 3 larval instars. The 3rd instar larva crawls to a drier area to pupate. Habits: Adults can often be found at flowers or on larval food materials which consist of moist decaying organic matter. Because they frequent such unsanitary places, they may transport various disease-causing organisms to food materials. Several species breed in human corpses and are commonly referred to as coffin flies when they become problems in morgues or mortuaries. They are of a great concern in health-care facilities because of their unsanitary habits, and because larvae have been found in the open wounds of patients.

Larvae breed in a wide variety of moist decaying organic matter which includes dung, fungi, and decaying plant material. Some are parasitic structures, breeding materials can include the moist organic film lining drain pipes, the moist residue in the bottom of trash cans, in elevator pits, garbage disposals, dirty moist mop heads etc. In offices, over-watered plants are often the source. Other sources can be the fresh-cut flowers in vases, soiled bedding materials in the bottom of animal cages, boot polish, glue paint, and leaky sewage pipes.

Follow the basic 5 steps of identification, inspection, sanitation, mechanical control/exclusion and insecticide application if required. The key is finding and eliminating all of the breeding sources. A residual insecticide is rarely required, though after the breeding sources have been eliminated a non-residual insecticide can be used to kill the adults present. A drain cleaning maintenance program may be needed with use of enzymes to destroy the breeding site.

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