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. Last Updated: 07/27/2016

Catnip Found To Naturally Repel Roaches

The stuff in catnip that intoxicates tabbies repels cockroaches 100 times better than a powerful insect repellent, scientists said Monday.

The discovery could lead to new nontoxic methods for curbing the insects.

Chris Peterson and Joel Coats of Iowa State University told a meeting of the American Chemical Society in New Orleans on Monday that they had isolated a chemical that even the loathsome roach finds repulsive.

Peterson and Coats began studying catnip a few years ago, when a summer intern told them the plant was resistant to insects.

"We decided to look at the chemical basis of that resistance,'' Peterson said.

So they boiled catnip leaves and distilled the active ingredient, a chemical called nepetalactone.

They discovered that a rare, potent form of nepetalactone killed flies. But the work might have ended there if another intern, Leah Nemetz, hadn't decided to study it as a repellent.

Nemetz soaked half of a piece of filter paper in the chemical and left the other side dry. Then she put the paper in a dish with some roaches and watched them scuttle away from the treated side.

Scientists tested their discovery against a widely used repellent called DEET. Their catnip-derived chemical worked at doses only 1 percent as high.

Iowa researchers have not tested the effectiveness of simply spreading natural catnip leaves around the house. It might require so much of the stuff as to be impractical, Peterson said. And, of course, it might attract a lot of cats.