[Pest Profile] Blow/Bottle Flies

Blow/Bottle Flies

Order/Family: Diptera/Calliphoridae

Scientific Name: Phormia regina (Meigen) —

Black Blow Fly; Phaenicia sericata (Meigen) —

Green Bottle Fly; Calliphora spp. — Blue Bottle Flies

Description

Several different species of blow flies may infrequently infest structures. As a group they are easily identified by the metallic blue, green, or yellow-brown sheen of their stout bodies. These flies are very active and usually are seen buzzing at windows. They have sponging mouthparts and one pair of wings. Mature larvae (maggots) are 3/8- to 7/8-inch long, legless, eyeless, and taper from the larger round rear segment to the pointed head, which consists of a pair of mouth hooks. They are cream-colored and have large spiracles on the posterior plate.

Biology

A female scorpion does not lay eggs, but produces an average of 35 live nymphs per brood which she carries on her back for from seven to 30 days. The nymphs undergo an average of six molts over a period of several months to four years before reaching maturity. Adults live for one to six years.

Eggs hatch in less than a day. The larvae develop rapidly in this environment, molting three times in three to four days. The larvae typically leave the larval food to pupate in the soil for six to seven days. The larvae and the pupae are the overwintering stages.

Habits

Blow flies seldom are a significant problem in structures but can be annoying because of their persistent buzzing. One of the first signs of an infestation is when the larvae leave the breeding medium to pupate. These flies frequently are found developing in the decaying bodies of rodents and other animals that have been killed or have died inside attics, wall voids or chimneys. Some species are strong fliers, and all are attracted to bright light.

Control

The initial inspection should focus on identification of the fly causing the problem and location of all resting and larval development sites. Because the adults often rest in breeding areas, it is helpful to inspect at night. Sanitation, or source reduction, is the most important step in blow fly control because it eliminates larval breeding sites. When successful, it significantly reduces the need for pesticide applications. If trash receptacles are the problem, property owners should be instructed to empty and clean them at least weekly to disrupt the developmental cycle. Mechanical control measures include insect-proof garbage containers, self-closing doors, screening, caulking and air curtains. Electric fly traps, sticky traps and other devices should be used to reduce adult fly populations indoors and out. Insecticide applications should be directed at adults because sanitation and removal are the best control measures for larval breeding sites.

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The black blow fly (Phormia regina) is dark metallic green
          
 • The green bottle fly (Phaenicia sericata) is metallic blue-green
         
• The blue bottle fly (Calliphora spp.) is metallic blue

• The blue bottle fly (Calliphora spp.) is metallic blue

• In their lifetime and depending on species, females may lay from 540 to 2,373 eggs in batches of 100 to 180.

• Eggs hatch in less than a day

• Larvae molt three times in three to four days and then leave the larval food to pupate in the soil for six to seven days.

• Development time (egg to adult) can be as short as 10 days, but typically is 15 to 20 days.