Blow Fly

Blow flies belong to the family Calliphoridae, a large and widespread group of true flies named for the older belief that they "blew" or contaminated meat by laying eggs on it. The green bottle fly, Lucilia sericata, is one of the most familiar and widely studied members of this family.

These flies are ecologically important decomposers, arriving at dead organic matter within minutes of exposure and helping to break it down rapidly. Because of the predictable timing of their life cycle, blow flies are also well known to forensic entomologists as indicators used in estimating time-related information at death scenes.

• Medium-sized fly, 8–14 mm long, with a compact, rounded body.
• Brilliant metallic green or blue-green sheen across the thorax and abdomen.
• Large reddish or maroon compound eyes and short antennae.
• Bristly legs and a single pair of clear wings with visible dark veining.
• Lookalike: very similar to the blue bottle fly but distinguished by its green rather than blue coloration.

Found on every continent except Antarctica, thriving in temperate to warm climates. Common in gardens, farms, and urban edges from spring through fall, blow flies are most active on warm, sunny days and are quick to locate exposed organic material outdoors.

Adults feed on nectar, plant sap, and liquefying organic matter, while females seek out decaying material to lay eggs, which provides a food source for the developing larvae. As decomposers, blow flies accelerate the breakdown of dead plant and animal matter, returning nutrients to the soil and serving as an important part of many food webs. Their flight is fast and darting, with a persistent, buzzing hover near food sources.

Blow flies undergo complete metamorphosis. Eggs, laid in clusters on decaying matter, hatch within hours into maggots that feed voraciously and molt through three larval stages over about a week. They then pupate in a hardened case, often in nearby soil, emerging as adults after roughly one to two weeks; several generations can occur each warm season.