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Tim Lockley: Spring, fall are gnats' favorite seasons here

"Noo, the wee midge is tiny, he's bloody minute

But, once he has bitten then he's no so cute.

See, the midge don't come in ones or in twos.

They come in their thousands looking for you.

You run like aneejit; you canny stand still.

But, they willnae leave tuil they've had their fill."

-- From "The Braw Wee Midge" by Maggie Pollock

It is thought that one of the reasons that contributed to the British treating Scotland so badly during their occupation was their having to contend with the Scottish midge. As bad as we have it with midges in the spring and fall of the year, in Scotland they swarm in clouds of blood-crazed no-see-ums, plaguing man and beast alike throughout the warmer months. Of course, in Scotland, the warm months are a fortnight in early August.

Biting midges are very tiny flies that are the bane of the gardener's existence. There are over two dozen species in Mississippi. Active throughout most of the year here on the Coast, their populations peak at the two times of year when the weather is most pleasant and you're ready to enjoy the out-of-doors. Most of their biting activity occurs during the early morning and again in the late evening but can happen at anytime during the day (especially if the sky is overcast) and throughout the night.

As with most parasitic flies, it's the females that do the actual biting. They need your blood for the protein. Without a blood meal, their eggs won't be viable Unlike mosquitoes which insert a needlelike proboscis into your skin and suck up blood, biting midges chew their way into your skin to form a puddle of blood and ruptured cellular material. That's why the pain is so far beyond what you'd expect from something so small. At least a mosquito injects a type of anesthetic. Once the midge has lapped up a little of your blood, she deposits her eggs in moist soil, usually around swamps or salt marshes. After the larvae hatch, they begin feeding on algae and other organic matter found in the moist soil.

Unfortunately, the immature midges are fairly impervious to any types of control we can use against them. Other than draining the wetlands, there's not much you can do. The adults, however, are readily killed by almost any insecticide. Fogging tends to be the most efficient method to use against the adults, but the effects are only temporary. During their peak population periods, adults are emerging from the ground almost continuously, and treated areas get repopulated very quickly. Fortunately, they are very weak fliers and don't travel too far from where they emerged. As a rule, the same controls you'd use for mosquitoes will work against no-see-ums.

For any of you who plan on working outside while the gnats are active, your best defense is an application of insect repellent. The traditional repellents containing DEET work very well against most biting flies. However, small children and pregnant women may want to avoid repellants based on DEET.

In the past few years, a new repellant has come on the market containing the active ingredient picaridin. Picaridin-based repellants are now as common on our shelves as those containing DEET. Picaridin has a number of advantages over DEET. It's safe for use by anyone of any age. It doesn't shatter watch crystals or melt plastic and rubber. And, best of all, it doesn't stink.

Some body lotions have also been reported to "repel" insects. However, research has shown these properties to be nonexistent. The lotions have no repellency. These lotions are primarily mineral oils. When applied to the skin, they form a thin film that acts temporarily as a barrier to small biting flies such as gnats. But, once the lotion is absorbed into the skin -- as it's designed to do -- that protection goes away. Nor do citronella candles or lamps have real effect against midges. If burned outdoors, they can afford some protection if there is no breeze. The smoke can hide your presence from a hungry gnat. They have the ability to locate their host by keying in on three things: CO2; enzymes and body heat.

They first detect your breath (CO2) and follow the concentration gradient. When they're closer, they switch to airborne enzymes which you also exhale. Finally, they home in on your body heat. If any of these keys are missing or masked, they can't find you. The smoke from the burning citronella oil can mask your CO2 and exhaled enzymes, but the slightest breeze will disperse the protective smoke and leave you visible to the midges.

And don't get your hopes up about "bug zappers." In order for an insect to get zapped, they have to make contact on two wires at the same time. Midges are too small (as are most mosquitoes). They just fly through the gaps. They are, however, weak fliers, and a well-placed fan can keep them away from you while you work and play outside.

Overall, your best bet for avoiding the gnatzis is to, first, try to work when the punkies are less active and to wear long sleeves, long pants, shoes with socks and a hat while outside.

Enjoy the cool weather while it lasts. The midges certainly will.

Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.

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