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Sand Flies
(also known as "Gnats," "Sand Fleas," "No-See-Ums,"
and "Punkies")

by
Dennis Adams
Information Services Coordinator

In High Sheriff of the Low Country (pages 84-86), the late Beaufort County Sheriff J. E. McTeer told of a nudist colony on Cat Island in the early 1930s. The project shocked the locals, but in the end it was "the stalwart and at times ferocious Beaufort County mosquitoes, red bugs and sand gnats (that) took their toll on the nudists' tender and exposed skins when spring arrived" and drove the naturists from Eden.

Because these "sand gnats" go by several aliases, including "sand flies," "sand fleas," "no-see-ums," and "punkies," I went to the Clemson University Extension Service office at #114 Carolina Cove (2201 Boundary St, Beaufort; 460-3655). As always, Mary Hagy was ready to help, and as quick as a sand fly's sting I had the answer from agent Jack Keener. He directed me to a University of Florida Cooperative Extension Service Web Site, "Mosquitoes and Other Biting Flies" (http://edis.ifas.ufl.edu/pdffiles/IG/IG08100.pdf), where I found these basic facts:

The Lowcountry is a paradise for sand flies (a type of biting midge), because they breed well in salt marshes, and the inland species lay their eggs in fresh water areas and tree holes. They are members of the insect order Diptera, the "true flies" like houseflies, horseflies and robber flies, which go through a full growth cycle from egg to larva to pupa to adult.

The larvae thrive in mud, sand, and debris near water surfaces, tree holes and on slime-covered bark. They swim freely in water and find shelter on floating leaves and other natural debris. The larvae grow into pupae in the debris or on the water's edge. David Arnold, former director of the Beaufort County Mosquito Control Department, told me that the six species of sand flies in our area are active at all seasons of the year and in various habitats. We can always expect six weeks of heavy activity during six weeks in the spring and six weeks in the fall. And you're sure to be bitten on cloudy days when the temperature is around 50 degrees F (but the effect of weather depends on the size and species that does the biting).

Sand fly species vary in size, but at less than a 1/16 of an inch long, they go straight through the 16-mesh screening on many windows and porches. If you magnified one of these little monsters, you'd see that adult sand flies are gray or black in color, with one pair of spotted wings and antennae in many segments. The drawing on the University of Florida Web page shows a creature that looks very much like a housefly to the untrained eye.

So why do these varmints bite humans so unmercifully? Just like mosquitoes, adult females need our blood to mature the eggs (the males don't bite).

Air movement affects to the activity of sandflies, and the adults of most species do not bite when there is a breeze or flowing air. The University of Florida Extension recommended that people "increase air mvement in screened prorches by using high velocity fans" to help prevent bites.

In her "Meanderings" column (Beaufort Gazette, March 21, 2002 ), Debbie Radford bemoaned the swarms of sand flies attacking people who rake the leaves on their yards here in the springtime. It so happens that people working outside raise their body temperature. Sand flies are sensitive to temperature and are drawn to humans and other animals with high body temperature. They annoy livestock and can even transmit nematode diseases to cattle.

In Beaufort County, sand flies transmit two viruses to the deer population. One causes clubfoot and the other virus produces an effect once blamed on food shortages in the woods: it starves the deer by preventing digestion of available nutrients.

But sand flies pose only a minor health problem to humans in the United States, who scratch insect bites that may later become infected. Sand flies are a much more serious matter in some other parts of the world. In Discover magazine ("Parasites and Bug Spit," August 1994), Josie Glausiusz reported that some Gulf War veterans contracted the parasitic, sand fly-transmitted disease, leishmaniasis, while serving in the Middle East. With thousands of Americans now engaged overseas in the "War on Terror," the U. S. armed forces are working to prevent any health risks to troops, and the County's Mosquito Control Department is working with the U. S. Air Force and Department of Agriculture on Parris Island to study the biology of sand flies and control measures (like pesticides and a Florida program that interrupts the growth of larvae and pupae into adult flies).

But can we control sand flies here? The primary mission of the Beaufort County Mosquito Control Department has been the control of mosquitoes since its creation in 1974, for reasons of both quality of life and health (there are 53 mosquito species in Beaufort County, and 25-30 of these are capable of carrying diseases). Past efforts have centered on control of the highly mobile salt-marsh mosquitoes (which can travel 9 to 10 miles per night), but the dangers of slower freshwater species have become clear with the emergence of the West Nile virus last year. Mosquito Control workload has doubled over the past three years, as methods for the trapping, study and control of all species of mosquitoes have increased.

So control of sand flies has been limited to some large public events (like Beaufort's 1976 Bicentennial Celebration). The Department now collects specimens of sand flies along with mosquitoes. There have also been some recent advances in control, but much testing must be done before pesticides and other substances can be put in the open water.

The University of Florida Extension recommends some measures for temporary relief. Certain "fog" products have inhibited sand flies around shrubbery and other hiding places, if used as directed. Screening finer than 16-mesh may help, and insect repellent may fend off "no-see-ums" for a few hours.

Can we say anything positive about sand flies? Yes, said David Arnold. Fishermen can count on fish biting the hook on the same days when "no-see-ums" are biting us. The ecological conditions that favor sand flies (water and soil temperatures, dense debris in the water) make the fish happy, too. That means, of course, that you will have to swat an awful lot of sand flies between catches.

 
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