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Take the sting out of your picnic

THANKS to entomologist Peter J. Landolt, we know a little better how to behave at picnics whenever a yellow jacket comes around. Whatever happens, do not stomp on the insect or otherwise flatten it. The effect would be to send out a call for help, and those that respond would be more annoyed than merely curious!

For weeks a yellow jacket nest had been increasing in size just outside the Insect Attractants Behavior Laboratory in Gainesville, Fla. (Florida State University), where Dr. Landolt works. Landolt's prime work is with fruit flies and the cabbage looper moth, but the more he noticed the yellow jackets, the more intrigued he became.

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Landolt noticed that whenever a truck or perhaps a lawn mower passed nearby, the wasps would become agitated and stay that way for a while. Obviously the ground vibrations triggered the anxiety in the first place. But why did returning wasps that had been away from the nest become agitated?

With colleague Robert R. Heath, Landolt was able to isolate and synthesize a chemical signal, pheromone, which the wasps give off to warn other wasps of real or fancied danger.

When just a whiff of the artificial signal was sprayed in the direction of the yellow jacket nest, guard wasps would respond. When some of the pheromone was spread on a piece of cloth, the scientists found that more than 500 yellow jackets responded and continued stinging for some three hours. The effect is the same if you squash a yellow jacket.

``Its venom sac breaks, and the alarm pheromone is released - which signals others to come to the rescue,'' says Landolt. He likens the effect to a police officer on patrol ``calling for backup help.''

The lesson from the experiment is obvious, entomologists say: Keep your cool in the presence of wasps, bees, or hornets, and the likelihood of being stung is remote.

These are some suggestions that will make your picnicking more enjoyable - if not entirely wasp free:

1.Before spreading the blanket in some unfamiliar spot, check around for insect activity. Yellow jackets frequently nest in old burrows in the ground or small hollows in a tree. Once I unintentionally put my hand on a nest that had been built in the hollow at the back of the door handle of a long-parked car. So expect the unexpected when you make your search. If you find a nest nearby, then prudence says look somewhere else to picnic.

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2.When a wasp comes visiting at your picnic table, be assured it's looking for food, not trouble. In other words, don't bother it, and it won't bother you.

Besides sipping nectar from flowers, wasps are meat eaters, feeding on grubs and other plant pests in the normal course of events.

So check your ham sandwich before you take a bite and also the sweet cool drink in your cup that a wasp will drink as a nectar substitute. It is recommended that children particularly be given cups with a plastic lid and a hole for a straw.

3.Watch out, too, for damp beach towels. Particularly in hot weather, wasps are on the lookout for moisture.

A wet towel is like a water fountain to a wasp. It alights and simply sucks up the moisture. The point is, don't sit down without looking.

4.Finally, whatever you do, resist the temptation to swat the visiting creature.

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