PHILADELPHIA (CBS) — It’s summertime, which means the return of the tiny, pesky insects — mosquitoes! Not only are they a nuisance, but they can also be a health hazard. That’s why Delaware County is taking action to protect residents from mosquitoes.

The Delaware County Health Department will be spraying residential and recreational areas Monday in an effort to control the mosquito population.

This comes after “high trap counts” and the identification of mosquitoes carrying the West Nile virus. Nearby Camden County, in New Jersey, also recently detected this year’s first “probable case” of West Nile Virus in Winslow Township.

Upper Darby Township, Lansdowne Borough and Yeadon Borough are among the areas being treated this round.

Spraying is scheduled to begin at 8 p.m. Monday and should be done by 11 p.m., weather permitting.

The Department of Health reminds residents to remain vigilant by using bug spray and watch for symptoms, like a fever or headache.

Additional spraying and testing will also be done in the area.

So far, at least eight cases of malaria have spread in the United States this year. It’s the first time since 2003 that the disease has been transmitted in the U.S.

The mosquito-borne illness can be deadly if not treated quickly.

Experts warn that rising temperatures nationwide could increase the mosquito population, which increases the chance of infection.