MOSQUITO CRACKDOWN BEGINS : CREWS BATTLE BUGS SPURRED BY WEATHER.

Byline: Michael Coit Daily News Staff Writer

Armed with insecticide and mosquito-eating fish, pest control crews are battling mosquitoes in earnest as hot summer weather speeds breeding and boosts populations across the region.

Mosquitoes breed throughout the year, depending on availability of stagnant water and warm temperatures. The greatest increase runs from July through September, when environmental health workers and abatement district crews target some 1,200 breeding grounds in Ventura County and about 500 more in western Los Angeles County.

Their aim is to keep mosquito larvae and pupae from emerging as adults that can carry diseases transmitted by animals and birds.

``They will go from an egg to an adult in a week's time. And one female will lay about 400 eggs,'' said Bob Saviskas, executive director for the Los Angeles County West Vector Control District.

A few inches of water is all the pesky insects need to hatch and emerge as adults.

Crews are doubled in summer to comb creeks, wetlands, drains and other sources of stagnant water. Ponds, pools and buckets containing water are troublesome breeding grounds because they usually are behind homes and aren't detected until neighbors complain about swarms of mosquitoes.

``It's gotten busy the last month. This week, the breeding period was about eight to 10 days,'' said Randy Smith, vector control director for the Ventura County Environmental Health Department.

Trouble spots have been found along drainage to the Santa Clara River near Oxnard and in agricultural expanses in the Fillmore area.

In Simi Valley, troublesome breeding grounds are found along the Arroyo Simi and near the hills in the Sinaloa area. The arroyos cutting through Thousand Oaks and Wildwood Regional Park are mosquito havens.

``We are finding some areas where the water is dissipating more than in the last couple of years, which is a benefit for us,'' Smith said.

There is a double edge, however, to the hot weather that helps eliminate wet breeding grounds: accelerated breeding periods.

Crews for the Ventura County and the Moorpark Mosquito Abatement District have a variety of lethal means to control breeding.

A thin sheen of oil can be sprayed on a water surface to suffocate larvae, or grains of bacteria that dissolve in water can be used to kill larvae. With a third method, briquettes that dissolve in water can be used to stunt growth, preventing larvae from becoming adults.

Residents can eliminate backyard sources by emptying buckets, trash cans and other containers that collect water and by keeping pools chlorinated and pumps and filters working.

Across the county line, the Los Angeles County West Mosquito Abatement District covers a 600-square-mile area centered in Culver City. The semirural expanse from Calabasas to Westlake Village and Malibu contains hundreds of mosquito breeding grounds, Saviskas said.

Abatement crews in both counties also use targeted trapping and monitor seasonal flocks of chickens to detect and track viral diseases.

The greatest concern is the potential spread of St. Louis encephalitis, which causes flulike symptoms and can lead to brain damage and death. Female mosquitoes require blood to become fertile and lay eggs, and they can easily spread the virus by biting a multitude of sources.

The L.A. abatement district expanded its trapping and tracking effort over the past several years in response to the detection of St. Louis encephalitis in county residents bitten by mosquitoes during the past decade, Saviskas explained.

``We can get a better coverage of the conditions,'' he said of the expanded trapping and tracking. ``Over the last few years, we've had spots where the chickens got infected.''

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2 Photos

Photo: (1) Robert Cueva pours mosquito-eating fish intoLas Virgenes Creek.

(2) Mosquito-eating fish will be deployed in the fight against the pests.

Jeremy Greene/Special to the Daily News