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Cheese Skipper
Cheese Skipper, a shiny black fly, 5 mm (0.2 in) in length, found throughout the world. It is best known for its problematic larvae (newly hatched wormlike forms) that live in human foods such as dried or processed meat, fish, and cheese. They are called cheese skippers not only for their habit of feeding on cheese but also because the older larvae can jump. They grab the folds of their own abdomen with their mouth hooks, tense their muscles, and then release their hold, flipping themselves 15 to 20 cm (6 to 8 in) in the air.
The adult female begins laying eggs about ten hours after mating. She will lay 140 to 500 eggs over her lifespan of three or four days. Eggs are laid in batches on or near food such as the muslin covers or wrappers of cured meat and fish. The larvae hatch a day later and burrow into the food. The older larvae are about 8 mm (about 0.3 in) long and cone shaped with a pointed front end. They have large mouth hooks that are used to tear up food. They pass through three larval stages and leave the food about five days later to pupate (transform into the adult form) in a dark corner or crevice. They emerge as adults after about eight days. Colder temperatures lengthen both development time and adult longevity. Larvae have been known to survive without feeding for up to six months at 9? to 10? C (48? to 50? F).
People sometimes eat cheese skipper larvae unsuspectingly because the larvae burrow deep into a variety of foods. The larvae are extremely hardy and can survive in the intestines of humans and other mammals. If accidentally eaten, they may cause a condition known as enteric myiasis, characterized by vertigo, violent abdominal pain, nausea, vomiting, and diarrhea with bloody discharge. The fly larvae cause these symptoms by cutting into the intestinal walls with their mouth hooks. Other species of flies may cause enteric myiasis but the cheese skipper is the most significant cause of this condition in humans.
Cheese skippers sometimes lay their eggs on human remains. The larvae can be helpful to forensic entomologists and police because they develop at constant rates, thus their size and stage of development provide clues to the time and conditions of death.
Scientific classification: The cheese skipper belongs to the family Piophilidae, in the true fly order Dipterais, and is classified as Piophila casei.
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