Being bitten by a mosquito can result in an itchy,...

Being bitten by a mosquito can result in an itchy, unsightly red bump and, occasionally, serious disease. Credit: Dreamstime/TNS

Nobody likes mosquitoes. Being bitten reliably results in an itchy bump and — sometimes — in serious disease.

About 50 kinds of mosquitoes live on Long Island and most don’t carry disease, according to the Suffolk County Department of Health website. But some female mosquitoes, which feed on blood to feed their eggs, can transmit West Nile virus and Eastern equine encephalitis virus to humans, the county said.

One way to keep mosquito numbers down around your home is to dump standing water. Mosquitoes don’t need much for their egg nursery, so get rid of excess water from containers around the home, including flower pots, clogged gutters and plastic toys.

The most effective way to fight mosquitoes once they’ve hatched is to use DEET, scientists say.

DEET (chemical name, N,N-diethyl-meta-toluamide) is the active ingredient in many insect repellents. It was developed by the U.S. Army in 1946 and should not be confused with the banned insecticide DDT, said Walter S. Leal, a University of California-Davis distinguished professor who has researched insects for more than 30 years and studied the effectiveness of DEET and other repellents.

The concentration of DEET in a product determines how long it will keep mosquitoes away. A product with 10% DEET will protect you for about two hours; a 30% DEET product works for five hours.

Young mosquitoes generally don’t carry disease and are simply a nuisance. But as mosquitoes age, their olfactory system becomes less sensitive, meaning they don’t smell the DEET as much, according to Leal.

So, to ward off older mosquitoes, you’ll need a higher percentage of DEET — somewhere between 20% to 30%.

Researchers have developed other insect repellents, but none lasts as long as DEET, he said.

Is DEET safe? The short answer? Yes. However, according to the American Academy of Pediatrics, kids should use insect repellents that contain no more than 30% DEET.

The Centers for Disease Control and Prevention said that pregnant and nursing women can use insect repellent, including DEET. Repeated research has found that DEET is safe for them when used as directed.

But DEET has a perception problem because unlike some repellents, it isn’t naturally occurring, Leal said. The public sometimes takes pause with that.

“They want something that’s natural — they forget that strychnine [and] ricin are all natural products,” Leal said, referencing poisons derived from plants. “Being natural does not necessarily mean it is good, and being synthetic doesn’t necessarily mean it is bad.”

Generally, DEET should be applied on bare skin, not under clothing.

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