Bed bugs less likely to bite hairy legs

You might like to think twice about hair removal, as researchers have found that body hair stops bed bugs from biting you.

The little blood-suckers actually seek out hairless areas on the wrists and ankles before settling down to have a meal - at our expense, according to Sheffield University researchers.

Some 29 volunteers took part in the study, which saw them have one armed shaved, and the other left naturally, before the bed bugs were placed on their skin.

The bedbugs took longer looking for the ideal feeding ground on people with more layers of longer (terminal) hairs and smaller, almost invisible, hairs (vellus) covering their arms.

The researchers said the sensitive fine hairs covering the body also act as a warning system, alerting us to bedbugs on our skin, as well as acting as a natural barrier.

Other parasites, including mosquitoes, midges, ticks and leeches, also are likely to favour relatively hairless areas of the body, the researchers said.

Professor Michael Siva-Jothy, of the University´s Department of Animal and Plant Sciences, said: "Our findings show that more body hairs mean better detection of parasites.

"The hairs have nerves attached to them and provide us with the ability to detect displacement. By forming a barrier and providing detection these hairs prolong search time and make detection more likely because the bug has to spend more time clambering over them.

"The results have implications for understanding why we look the way we do, what selective forces might have driven us to look the way we do, and may even provide insight for better understanding of how to reduce biting insects' impact on humans."

However, men appear to be bitten just as much as women, despite being hairier.

"Men have more body hair than women, which is caused by the action of testosterone at puberty.

"This does not necessarily mean that women are more likely to be bitten. Blood-sucking insects are likely to have been selected to prefer to bite hosts in relatively hairless areas," Prof Siva-Jothy said.

And being overly hairy does not appear to put you at an advantage either.

"If you have a heavy coat of long thick hairs it is easier for parasites to hide, even if you can detect them.

"Our proposal is that we retain the fine covering because it aids detection and if we lost all hair, even the relatively invisible fine hair, our detection ability goes right down," Prof Siva-Jothy said.

The study is published in the Royal Society journal Biology Letters.

This article was published on Thu 15 December 2011