Extension > Garden > Diagnose a problem > What insect is this? > Insects found indoors > Winged Insects - 1/4 inch up to 1/2 inch > Blow flies, Family Calliphoridae

Blow flies

Calliphoridae family

Jeff Hahn, University of Minnesota Extension

Jeff Hahn, University of Minnesota Extension

Description: 1/4 - 1/2 inch long. House fly-like; bodies are metallic green or gold.

Where/When: Typically an outdoor insect. They are sometimes found indoors during the summer, as well as occasionally during the fall.

Significance: Blow flies are usually associated with decaying animals, excrement, or other sources of decaying organic matter. When found indoors during the summer, especially when large numbers suddenly appear, they are probably associated with a dead animal in a wall void, attic, or similar place.

Small numbers of blow flies may enter buildings in the fall and become a nuisance. Since blow flies are associated with waste and decaying matter, they can potentially be a vector of disease-causing bacteria. Blow flies do not bite.

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