SAN DIEGO (CNS) - With temperatures rising and summer approaching, San Diego County officials announced Friday they will soon begin dropping mosquito larvicide on approximately 48 rivers, streams, ponds and other waterways.

Starting Wednesday, county Vector Control Program employees will use a helicopter to drop batches of granular larvicide on waterways about once a month during mosquito season to help protect the public from illnesses such as West Nile virus. The larvicide does not hurt people or pets, according to the county, but kills mosquitoes before they can mature.

Employees will treat more than 1,000 waterway acres stretching from Chula Vista in the south to Fallbrook in the north and from Oceanside in the west to Lakeside in the east.

The larvicide drops comprise one part of Vector Control's yearly mosquito-control program, which includes treating potential mosquito-breeding areas by hand, giving out free mosquito-eating fish to the public, treating neglected swimming pools and testing dead birds for West Nile virus.

Residents are encouraged to follow their own mosquito-abatement exercises, such as dumping standing water from plant saucers, rain gutters, buckets, garbage cans, toys, old tires and wheelbarrows. Experts said recreationists should wear long sleeves and pants when outdoors or use insect repellent.