Cheese flies

Morgan Adams


  • Also known as cheese skippers
  • These flies receive their name due to the unusual ability of the larvae to propel themselves through the air.
  • The flies are detritivores, feeding on decaying matter, and even have been found on the exhumed remains of Egyptian mummies
  • Small metallic-colored flies, usually black/bluish-black with bronze-colored tints on the head, thorax, and abdomen, with reddish-brown eyes and iridescent wings
  • Males are 4.4-4.5 mm from the tip of the head to the tip of the wings, whereas females are slightly larger, usually measuring 5.0-5.2 mm.
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  • Attracted by strong smelling foods such as cheese, ham, bacon.
  • Waste, feces and contaminated materials are also included in the diet
  • Usually feed on overripe (three or more months old) and moldy cheese

Geographic location

  • Cheese skippers have a worldwide distribution, including the United States, and are not limited to any specific geographic location
  • Larvae are typically found on high-protein substrates ranging from salted beef to smoked fish and animal carcasses

Life cycle

  • Undergo complete metamorphosis.
  • Females mate almost immediately after adult emergence
  • The complete life cycle of a cheese skipper in appropriate nourishment and temperature conditions can be as short as 12 days (1 day for egg development, 5 day larval maturation, 5 day pupal maturation, 1 day of adult feeding before reproduction). However, the typical life cycle is as follows: Egg ~23 to 54 hours - Larva ~14 days - Pupa ~12 days - Adult ~3 to 7 days.
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Time appears on body

  • Forensic entomologists have used the presence of Cheese flys larvae as a tool to assist in the estimation of time of death for human remains.
  • Though they can appear on remains less than two months old in geographic locations such as Florida, the flies sometimes do not appear on an exposed corpse until three to six months postmortem (after death), usually after the body has completed the "active decay" decomposition stage and is beginning to dry

Additional Information

  • Sardinia’s infamous casu marzu cheese begins its life as a fairly standard pecorino, a hard cheese made from sheep’s milk.
  • Once this pecorino has had a chance to cure, the cheese is opened up – typically by slicing the top rind off like a lid – and the exposed cheese is left outside in order to attract flies.
  • These so-called “cheese flies” lay their eggs inside the pecorino wheels, and when the larvae start eating their way through the cheese is when it really becomes casu marzu.
  • This changes the flavor and texture of the cheese. It goes from being a relatively standard, hard pecorino to a softer and stronger cheese inside a hard shell.
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Work cited