Flesh Fly

Flesh flies make up the large family Sarcophagidae, with more than 2,500 species distributed across nearly every region of the world. Their common name refers to the diet of many species' larvae, which develop on carrion, dung, or other decaying organic material, making them important decomposers in most terrestrial ecosystems.

Adult flesh flies are somewhat larger and bristlier than the common house fly, and their distinctive gray-and-black checkered abdominal pattern combined with three bold stripes on the thorax makes them fairly easy to recognize once you know what to look for.

Because of their reliable and rapid attraction to decomposing tissue, flesh flies are also of interest to forensic entomologists, who use the predictable timing of their life cycle stages to help estimate how long a carcass has been present in a given location.

• Gray body, 6-14 mm long, noticeably bristlier than a house fly
• Three bold black longitudinal stripes running down the thorax
• Checkered black-and-gray pattern on the abdomen, sometimes with a pinkish or coppery tip
• Large reddish eyes in many species
• Lookalikes: house flies lack the thoracic stripes and checkered abdomen; blow flies have a metallic blue or green sheen that flesh flies lack

Flesh flies occur nearly worldwide except in the coldest polar regions, found wherever carrion, dung, or decaying organic matter is available. They are common in gardens, woodlands, farmland, and urban lots, and are frequently among the first insects to arrive at animal carcasses or exposed garbage.

Adult flesh flies feed on nectar, plant sap, and liquids from decaying organic matter, while larvae are scavengers that develop on carrion, dung, or discarded food waste, helping break down organic material and recycle nutrients back into the ecosystem. Some species are more specialized, developing as parasitoids of other insects such as grasshoppers or beetle larvae. Adults are strong, fast fliers and are often among the earliest visitors to a fresh carcass, a trait exploited in forensic entomology to help establish a decomposition timeline.

Unlike most flies, flesh flies are ovoviviparous: rather than laying eggs, females retain fertilized eggs internally until they hatch, then deposit live first-instar larvae directly onto a suitable food source such as carrion or dung. The larvae pass through three instars while feeding, then leave the food source to pupate in nearby soil. In warm weather the entire cycle from larviposition to adult emergence can take as little as one to two weeks, allowing for many overlapping generations per year.