Dear Tom,

Why do flies bite so ferociously right before a rain storm?

Donna Hirsch, Worth

Dear Donna,

We posed your question to Dr. Ken Paige, professor and Associate Head of the Department of Animal Biology at the University of Illinois, Champaign-Urbana.

Dr. Paige stated that the flies along with other insects are likely responding to falling barometric pressure preceding the rain event. He feels that the insects adaptively feed to survive through the bad weather.

Insects are also cold-blooded and become more active as the temperature rises. In summer, the hot and muggy conditions before many rains not only increase insect activity, but cause us to sweat and emit body odors that may also attract the insects.

----------

Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN News at noon and 9 p.m.

Send your questions to:

ASK TOM WHY, 2501 Bradley Place, Chicago, IL 60618

e-mail: asktomwhy@tribune.com