I got these clear shots of a flesh fly (Diptera: Sarcophagidae) in a nearby Michigan floodplain forest the other day. While similar in appearance to blow flies (Calliphoridae), house flies (Muscidae), and tachinid flies (Tachinidae), there are many features that set this family apart. Many minute characteristics of the bristles, antennae, and wing veination are used to identify this family, but two obvious features can be used for a preliminary identification. First, flesh flies generally feature three black stripes against a gray background on the thorax. Second, these flies are never metallic. Some blow flies have similar stripes, but are metallic to some degree (Triplehorn and Johnson 2005). A nice photo I took a couple of years ago shows a flesh fly next to two different blow flies, and is useful for a comparison.
Adult flesh flies feed on sugary substances like nectar, sap, fruit juices, and honeydew (Triplehorn and Johnson 2005). Larvae, in contrast, generally feed on animal material like rotting flesh, and that’s what gives this family its common name.
Triplehorn, C.A. and N.F. Johnson. 2005. Borror and DeLong’s Introduction to the Study of Insects. Seventh Edition. Thomson Brooks/Cole, Belmont, CA.