Helps Control Diseases : Mosquito ‘Swat’ Team Lessens Summer’s Sting

They thrive beneath dead bouquets in cemetery flower vases. They lurk in discarded tin cans and abandoned tires.

Summer is their season and, left to their own small devices, they multiply in staggering numbers. A single unkempt swimming pool can become an Olympic-sized nursery for a million or more.

The creatures are mosquitoes, unlovable little insects that can make summer a misery with their bites and can transmit such genuinely dreadful diseases as encephalitis and malaria.

There are remarkably few mosquitoes in much of Los Angeles because of men like Mark Brooks, one of the exterminating angels of the Los Angeles County West Mosquito Abatement District, headquartered in Culver City.

Mosquito Zappers

Brooks, 33, who lives in Mar Vista, is one of the district’s dozen full-time employees, a deadly cadre of mosquito zappers who seek and destroy the insects from the gurgling creeks of Malibu to the horse troughs of Rolling Hills Estates, from the sumptuous back yards of Beverly Hills to the littered concrete floor of Ballona Creek.

In summer, the full timers are joined by nine seasonal employees. They chase their prey with specialized equipment that includes trucks with the steering wheel and a door-mounted tank of pesticide on the right, so the driver can spray a curb-side infestation and drive at the same time.

Like his counterparts in the three other mosquito abatement districts in Los Angeles County, Brooks is used to people laughing when they hear what he does. But Brooks knows his job is important. “Without the mosquito abatement district, there would be encephalitis, there would be malaria, and it would be no joke.”

Indeed. Worldwide, mosquitoes are the insects most dangerous to human health. They are carriers--or vectors, as public health officials call them--of a host of diseases, including yellow fever and dengue fever.

Tar Pits Still Tricky

Of the 600 square miles that Brooks and his colleagues patrol, perhaps the hottest single spot is the La Brea tar pits in Hancock Park. The tar pits, which once doomed mastodons and saber-toothed cats, are now odoriferous pools of asphalt and water that attract Culex tarsalis , a mosquito that can transmit encephalitis, a sometimes deadly inflammation of the brain.

“Millions would hatch out every night if we didn’t spray,” Brooks said. Every Monday, when the museums are closed and few visitors are in the park, a mosquito abatement crew blankets the tar pits with a petroleum product called Golden Bear that floats on the surface of the water and suffocates any mosquito larvae present.

“It’s a guaranteed kill,” Brooks said.

Hancock Park is also the home of the district’s flock of “sentinel” chickens. As Brooks explained, the district keeps two dozen laying hens in a coop in the park to serve as an early warning system for encephalitis.

Blood is drawn from the chickens each month and sent to a laboratory at UC Berkeley, where it is examined for evidence of the virus that causes encephalitis. Although an occasional chicken tests positive, there have been no reported cases of human mosquito-borne encephalitis locally since 1984.

Diversified Methods

In the old days, DDT and other dangerous chemicals were used to kill adult mosquitoes. Today the abatement crews work at destroying the larvae with relatively benign agents, including mosquito fish. Brooks said the Westside district distributes about 25,000 of the gray, guppy-like fish each year. Many are given free to homeowners to put in their fishponds. The fish also work in horse troughs, Brooks noted. “When the horse goes to drink, the fish will just dive.”

The computers that are now a feature of mosquito abatement in Los Angeles keep track of thousands of spots where mosquitoes are known to multiply, including the holes left in the ground when oil derricks are dismantled. New construction often creates breeding grounds, and a major fire can turn a neighborhood’s swimming pools into entomological time bombs. After the Baldwin Hills fire, dozens of back-yard pools were added to the district’s route books for regular inspection and treatment.

To help pinpoint problematic pools, a mosquito-abatement technician often flies along when County Sheriff’s Department helicopters are out on surveillance or pursuing suspects. The film is turned over to the county Health Department, which scrutinizes it for murky pools and alerts the relevant abatement districts.