The cold chill of fall spells big trouble for a couple of life’s little annoyances.

A frost over the next few days is expected to put an end to the mosquito season.

“We’ve had so little mosquito action this year that the cold weather has probably eliminated most of them already,” said Karen Grush, public health administrator at the DeKalb County Health Department.

As of Sept. 29, Illinois reported 19 cases of West Nile virus, which is carried by mosquitoes, according to the Centers for Disease Control and Prevention Web site, www.cdc.gov.

“It was in the low 30s [on Sunday],” Grush said. “Any that are left are probably looking for places to hide.”

They do not have a lot of time to find a hiding place, however.

NIU staff meteorologist Gilbert Sebenste said the frost is expected to increase throughout the week.

“We should see a hard frost [today] and Thursday morning,” he said.

The hard frost should eliminate the mosquitoes that the cold weather has not eliminated already.

“It will probably kill them off as temperatures drop past freezing,” Sebenste said. “Bees and other pests that annoy people will be killed off as well.”

Not only will the frost end the mosquito season, it also will provide some relief for many allergy sufferers.

“The first frost kills off ragweed,” Sebenste said. “The ragweed count should be close to zero after the frost.”

Ragweed causes runny noses, coughing, watery eyes and other symptoms, Sebenste said.

The growing season also is expected to end as the first frost rolls in, Sebenste said.

Mariam Wassmann, director of information for the DeKalb County Farm Bureau, said the threat of frost is not much of a concern for most farmers.

“At this point, they are done growing anyway. Corn and soybeans are in a drying stage,” Wassmann said. “Oct. 5 is the average day for the growing season to end, so this is pretty normal.”