[Pest Profile] Cheese Skipper

Order/Family: Diptera/Piophilidae Scientific Name: Piophila casei (L.)

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May 31, 2005

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• 3/16-inch long

• Cheese skipper is black and shiny

• Bronze tints on thorax

• No markings on top of prothorax

• Reddish brown eyes

• Lapping (sponging) mouthparts, similar to those of a house fly

• The body is long and thin, and its slightly iridescent wings fold flat over the body

• Found throughout the United States and is a significant pest of cheese and meats

• The cheese skipper gets its name from the fact that the larvae appear to move about by “skipping”

Description

The cheese skipper is a small, black fly about 1/8- to 3/16-inch long with reddish- brown eyes and bronzy tints on its thorax. The body is long and thin and its slightly iridescent wings fold flat over the body. It has lapping mouthparts similar to those of the house fly.

Biology

The cheese skipper gets its name from the fact that the larvae appear to move about by "skipping." Larvae have been observed jumping as far as 10 inches. This fly is found throughout the United States and is a significant pest of cheese and meats. In addition to cheese, cheese skipper larvae have been found living in ham, bacon, human cadavers and manure. The female cheese skipper will deposit eggs onto an appropriate food source. The larvae avoid light and will burrow into the breeding material. Under ideal conditions, the entire process from egg to adult can occur in as little as 15 days, but adverse living conditions can stretch this period to as long as eight months. The adults feed on the juices present in the larval breeding source and live only a short time to mate and lay eggs.

Habits

Facilities which process, package or store cheese and meat products are the most likely structures where cheese skippers will be found. Rendering plants where livestock is butchered and processed may also experience infestations of these flies.

Control

When looking for breeding sources of cheese skippers, keep in mind that the source must be moist. Dried meats rarely will be infested. Overripe and moldy cheese and cured ham products are the preferred breeding sources. Even small amounts of grease or food trapped in cracks of equipment can support cheese skipper larvae. Damaged food products in warehouses are often a source of these flies. Finding damaged goods in this situation may be difficult, however, the smell produced by the decaying food product can help narrow the search area. Focus on areas where canned meat products are stored.

Because the larvae and adult flies feed on decaying organic materials, they come into contact with organisms which could cause human disease. It is suspected that cheese skippers can transmit these organisms to food products in a similar manner to house flies. Persons who eat foods containing the larvae of cheese skippers can experience intestinal irritation.