Origin:
The true origin is unknown, as these flies are found throughout the world.
Biology:
This is a large filth fly found in and around structures, and its presence indicates that larval food resources such as animal feces or a dead animal are present. The adult flies often overwinter, commonly within structures, and they may appear within the structure during warm winter days. They are drawn to light, such as windows and doorways. The maggots are commonly found in fresh wounds in humans or animals and are even used in medical maggot therapy. The life cycle from egg to adult fly ranges from 10 to 25 days, depending on temperature, and the maggots pupate in the soil or beneath the carcass they have been feeding on.
Identification:
Despite its common name this species is usually a shining metallic blue color, whereas the “blue” blow fly discussed separately has a dull black thorax and blue abdomen. Species of Phormia have a pair of orange spiracles on the front of the sides of the thorax and there are 3 faint stripes running down the back of the thorax. The larvae of Phormia are typical “maggot-shaped” with a strongly narrowed head and widened posterior. The spiracles at the posterior end are set within a depressed ring that has short “spines” around it.
Characteristicts Important to Control:
The presence of blow flies in and around structures indicates there are food resources for the larvae, as the adults are strongly attracted to the odors of rotting organic materials. Meat is a favored food of the larvae and dead animals within structures will breed large numbers. Finding the food resources and eliminating them is necessary for complete control of the problem.
