Blow flies are a diverse category of fly, although they are typically similar to house flies in both size and shape. Ranging from a quarter of an inch to half an inch in length, these flies can be metallic blue, black, or green in color depending on the species. The larvae of these flies feed on carrion and dung.
In general, each female blow fly deposits thousands of eggs over her 2 to 8-week lifespan. Egg masses can consist from 40 to over 1000 eggs. The eggs are laid on animal carcasses or in garbage or feces, any area with decay. Incubation of the eggs is around 4 days, but hatching can occur in less than 24 hours in warm and humid conditions. Once hatched, the larvae, known as maggots, will feed on the dead material around them. While they typically only feed on the dead matter, some species of blow fly larvae has been known to also damage and feed on living tissue. This is most common if the larvae encounters an open wound, however can also occur on unbroken skin.