Spring 2004

Out in the Field:
How to Ward Off Them That Suck

By Craig Vetter

Richard Lampman, an entomologist with the Illinois Natural History Survey who is in frequent contact with mosquitoes, recommends repellent — "something with ten percent DEET in it. You don't need it any stronger than that. The natural repellents — citronella, garlic extracts, things like that — don't last very long and aren't as effective as the DEET products."

Many health officials also have recommended staying indoors at dawn and dusk, when many mosquitoes are biting. Yet this is precisely when many nature enthusiasts love to be out, finding the best migrating birds, catching the best light to photograph wildflowers, having the prairie or woods all to themselves. To these people, these instructions may sound just as unrealistic and unfun as another commonly heard recommendation to stay indoors all summer to avoid skin cancer.

But mosquito-borne illness, though statistically low-risk in this region, is a reality. Nature explorers may want to balance limited repellent use with judgment about when to head outside during August and September, the heaviest feeding times for the mosquito that carries West Nile virus. Wearing long-sleeved, loose-fitting clothing will also help.

According to Lampman, scientists don't know for sure why mosquitoes bite some people more than others. "But," he said, "it's fairly well suspected that thermal signature (how hot you are), the carbon dioxide you exhale, along with other odors you give off (many of which are undetectable by humans) are the main attracters."