Black Blow Fly (Phormia regina) — identification, habitat & look-alikes

The black blow fly is one of the most common blow flies at carcasses and death scenes in North America, which makes it a key insect for . Investigators use the growth stage of its maggots to estimate how long ago a death happened. Adults are dark, metallic blue-green flies with a black face and orange hairs near the front of the thorax.

Appearance

Appearance: A metallic blue or green fly with black cheeks, mostly white flaps (calypters) at the base of the wings, and orange hairs around the front breathing hole () on the thorax.

Look-alikes

Northern blow flyProtophormia terraenovae

Both are dark and metallic, but the black blow fly has bright orange hairs around the front thoracic spiracle, while the northern blow fly's spiracle is black to brown. You need a close-up photo of the side of the thorax to see it.

Why they get mixed upSimilar size and dark metallic color, and both are cool-season flies found from Canada into the US.

Common green bottle flyLucilia sericata

The green bottle fly is a brighter, shiny green. The black blow fly is darker and duller blue-green.

Why they get mixed upBoth are metallic blow flies found together at carcasses.

Where it lives

Typical habitats: Animal carcasses
Animal dung
Range: Common across the United States and the rest of North America. In the northern states it shows up mainly in spring and summer, and in winter it is found only in the South.
Preferred conditions: A cool-weather fly. Females stop laying eggs below about 55°F (12.5°C), and larvae rarely make it to adulthood at 104°F (40°C) or above, which may help explain its seasonal shifts. In one study around the San Francisco Bay Area, it preferred rural spots near water over cities.

Behavior

Diet: Adults sponge up food and, in the wild, get most of their nutrition from dung. Females need protein to mature their eggs. Larvae feed on carrion.
Social life: Adults gather on dung both to feed and to find mates.

Life cycle

Reproduction: Females lay eggs on carrion and leave; there is no parental care. Smell guides where they lay.
Larva: Maggots pass through three growth stages before pupating. At a constant 95°F (35°C), egg to adult takes about 11 days; cooler temperatures slow things down. Big masses of maggots heat themselves up, which may help them feed and grow.

Cautions

Cautions: The larvae can infest wounds in people and animals (), especially in the southern US.

Conservation

IUCN Red List: NENot EvaluatedNot yet assessed

Culture and stories

Culture and stories: Disinfected live maggots of this fly are used in maggot therapy to clean dead tissue out of wounds.
The species name regina is Latin for "queen."

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