Blow Flies

Facts, Identification & Control

Latin Name

Family Calliphoridae

Appearance

Blow flies are often metallic in appearance, with feathery hairs on the terminal antennal segments of the males. Adult blow flies have sponge-like mouth parts, while maggots have hook-like mouth parts.

Behavior, Diet & Habits

Blow flies belong to the Family Calliphoridae of flies under the Order Diptera. To date, there are approximately 80 species of blow flies in North America.

Blow flies are attracted to decaying meat and are typically the first organisms to come into contact with dead animals. The meat of dead animals is essential for larval survival and growth. They are also attracted to plants that give off the smell of rotting meat and as such, can be a pollinator for those plants.

Reproduction & Life Cycle

life cycle chart

Larvae or Maggots
Female blow flies typically lay their eggs on decaying meat, where maggots hatch within a few hours to a few days depending on species. These maggots undergo three stages within several days, after which they leave their food source and pupate in soil. Within a few  days, the pupation will be complete, at which point they emerge as adults.

Appearance
Blow fly larvae are also known as maggots. Measuring 9 to 22 mm in length, maggots are equipped with hook-like mouthparts and spiracles for breathing. They are soft and pale in color and appear similar to worms or grains of rice. Each body segment of the blow fly maggot has a median row of fleshy tubercles that resemble hair.

Blow fly maggots are generally seen near dead animals. Blow fly eggs are laid in rotting meat, where maggots feed and complete their development before seeking a dry location within which to pupate. After maturing, larvae create outer skins, known as puparia, that look like rat droppings or cockroach egg cases. Pupae develop within the puparium, maturing into adult blowflies.

Different species of blow flies are active at different times: the Calliphora vomitoria are most commonly found on carrion during cooler months, while the Phaenicia sericata are more active in hot seasons. Other species thrive more in the shade, while some require hot temperatures to complete the maggot developmental stage.

Signs of a Blow Fly Infestation

The most common signs of blow flies are either the adults themselves or their larvae.  The adults may be seen resting on surfaces or buzzing around potential food or odor sources. The larvae may be observed when they crawl out of the breeding material to pupate.