Tour de Fly

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Published on: May. 2, 2003

Last revision: Nov. 15, 2010

scene of death within minutes, while other species follow later, in a predictable sequence. Time of death can be accurately estimated by establishing which species are present on a corpse, and at what stage of development.

Phormia and Phaenicia have helped living people, too. During World War I, and shortly thereafter (early 1930s), sterile maggots were employed to clean wounds. The larvae eat only dead tissue, while secreting an antibacterial chemical that retards infection. To this day, maggots are still used in difficult cases of deep bone infection (osteomyelitis).

Flesh flies in the family Sarcophagidae also exploit carrion. Sarcophaga haemorrhoidalis are black and gray with scarlet eyes and "tails." The females arrive at a carcass later than blow flies, but catch up by laying live maggots instead of eggs. They can also find bodies indoors, where few other flies will search.

Tick-like, with flattened bodies and grappling hook claws, the louse flies (family Hippoboscidae) are truly bizarre. The wingless "sheep ked," Melophagus ovinus, is a familiar bane of livestock owners. Otherwise, hunters are the ones most likely to see these secretive parasites.

Larval hippoboscids develop one at a time, inside the female fly, feeding on milk-like glandular secretions. "Born" as fully grown larvae, they pupate immediately, on the host or on the ground. Most species emerge as flying adults, but some break off their wings after dispersing and settling on another host.

Louse flies feed on blood. Many, like the squab fly, Pseudolynchia canariensis, are common on pigeons or other birds, and sometimes serve as living ferries for feather lice. Lipoptena depressa occurs on deer.The world of flies is full of many more amazing stories, some yet to be deciphered. So, before you swat that noisy nuisance, you might want to contemplate its beneficial qualities. Or, maybe not.

Controlling Common Flies

Some folks swear by an unusual method of repelling house flies. They fill a clear plastic ziplock bag half full of water, and attach it to the outside surface of a door or window. No one is clear on why this works, but it does.

Flypaper still works well indoors, trapping flies that alight on the sticky yellow ribbon. Fly swatters are even more entertaining and rewarding. Pesticides are not recommended, to avoid contamination of foods and dishware.

A new trap, dubbed "Flybrella" by its creators at the USDA-ARS, is now approved for use in restaurants and other indoor settings.

Sanitation and exclusion are still the best preventive measures. Make sure trash cans are securely covered and emptied regularly. Dispose of manure and other organic waste quickly. Patch holes in screens and seal openings to the outdoors around pipes and electrical conduits.

Controlling horse and deer flies is virtually impossible. Avoidance is the best strategy. Donning a hat keeps deer flies off your scalp, and wearing light colored long sleeve shirts deters bites on extremities. Using repellents containing DEET is recommended, but never apply such chemicals to your skin. What residues are not absorbed will be quickly sweated off anyway. Using repellents on children is especially risky.

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