Bats battle bugs - help you, your garden

A few years ago, Merlin D. Tuttle, a professor at the University of Texas and founder of Bat Conservation International, approached a Tennessee farmer with a request: Might he investigate a cave on the farm that housed a bat colony? ``Sure,'' the farmer replied, ``and if you can find a way to get rid of them while you're there, go ahead.''

Hours later, Dr. Tuttle emerged from the cave with a handful of insect wings. Dumping them in front of the farmer he asked: ``Know what these are?'' ``I'll say I do,'' the farmer replied. ``They're Colorado potato beetles. They can do a number on a potato field! Where'd you get 'em?''

When told that the wings came from the cave, and that potato beetles obviously were a major part of that particular colony's diet, the farmer's attitude toward bats did an about-face. Given a rough assessment of the beetle wings still back in the cave and the approximate size of the bat colony, the farmer did some quick calculations. ``I reckon each bat is worth about $5 to me [in reduced crop losses],'' he told Tuttle.

To Tuttle and his colleagues at Bat Conservation International, this represents a small victory in the ongoing and often frustrating campaign to get people to recognize the value of bats and to prevent the extinction of bat species that is taking place worldwide. ``Last year two bat species became extinct on the island of Guam alone,'' says Tuttle. ``We are losing entire species even before they make it onto the endangered species list.''

Loss of summer roosting sites (hollow trees, suitable rock overhangs, etc.) and the spread of urban centers is partly responsible. But two other factors, particularly in the United States, are a widespread public fear of bats, built up by totally false stories in popular magazines, and misleading advertising by pest exterminators.

But apart from potato farmers, who else would benefit from having bats in the neighborhood? We all would. For one thing, bats will do more to make the evening barbecue mosquito-free than any other wild creature. And they can do great things for the garden, too.

With its incredible sonar system, the bat easily detects and avoids objects in its path, including thin wires, even when blindfolded during scientific tests. For this reason, scientists dismiss stories of bats becoming entangled in human hair as ``old wives' tales.''

What do attract bats and bring them flying near people on a warm summer evening are insects, particularly mosquitoes. The mosquito senses the warm-blooded human presence and zeroes in. In turn, the bat picks up the mosquito's presence and flies close by, and it's likely that the human being has been spared one more mosquito bite, says Tuttle.

There is also a fear that bats are more likely to become rabid than any other animal. This is not the case, Tuttle points out. Moreover, the bat that does become rabid quickly becomes immobile and dies, making it far less of a threat in this respect. Bats do not fly out and attack people. On the other hand, however, if you push a probing hand into a darkened area and disturb a sleeping bat, it is very likely to bite.

Moths are another major item in the bat diet, and the fact that both cutworms and the peachtree borer are the offspring of night-flying moths indicates why the presence of bats is so valuable to the gardener. An occupied bat-house, where guano drops conveniently to the ground below, is another plus. Bat guano is a remarkably rich fertilizer. Like penguin guano, it sells for as much as $30 a pound ... when it can be had, that is.

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