On the first day of summer today, there are new gunslingers in town that want to rough us up and spill some blood.

But the local marshal, determined to keep order, has offered recommendations to prevent the hungry marauders from tapping the veins of the local population.

There's nothing good about these villains, including an Asian mosquito, Aedes japonicus, that hit American shores in 2000 and then spread like wildfire nationwide in eight years.

The bugs breed in small collections of stagnant water containing decomposing grass and leaves.

"The blocked gutter is the perfect place for them," said Bill Todaro, medical entomologist for the Allegheny County Health Department. "If you don't clean out your gutters, and do it three or four times a year, they will breed mosquitoes."

Yesterday, health department officials began treating 22,000 storm-water catch basins countywide with pesticides to help control the mosquito population, including the Asian mosquitoes. The county hopes to reduce nuisance mosquitoes and prevent West Nile virus infections of people.

West Nile, yet to be detected in the county this year, is expected in due time.

The pesticides prevent mosquito larvae from maturing into adults for about a month. The pesticides are available for private properties by calling 412-350-3886.

"We found that if we act to prevent the breeding, the incidents of West Nile virus are lowered," Mr. Todaro said. "We trap mosquitoes all summer and test them for the virus, and if we're able to cut down on the vector populations, we cut down on the number of positive cases."

Another recent arrival is the long-anticipated deer tick, Ixodes scapularis, which hails from Connecticut and has become the most common tick in Allegheny County -- even more common than the dog tick.

The deer tick spreads Lyme disease, which can cause fatigue, headaches, fever and a rash in early stages then progress to joint, nervous system and heart problems if left untreated.

"We're only getting 20 to 30 documented cases of Lyme disease per year, but the tick will spread bacterium to mice and build a reservoir of Lyme disease in mice, then see it spread to people," Mr. Todaro said.

Ticks benefit from moist layers of soil with layers or roots and decomposing leaf and grass litter.

Another new pest whose bite is painful without longer-term consequences is the stable fly, which looks like the common house fly. It breeds in areas where dogs or other animals urinate because it prefers a high nitrogen environment. It bites dogs and humans and is common around zoos.

Insect repellents, clothing covering arms and legs and elimination of stagnant water are key defenses against bugs, Mr. Todaro said.

Recent rainy weather has raised the specter of a potentially buggy summer. Mosquitoes and flies "certainly benefit from a lot of rainwater being deposited in the yard," he said.

But Lee Hendricks, a National Weather Service meteorologist, said the county has had only 2 inches of rainfall this month, 0.4 inches less than normal and less precipitation than we had last year.

In the year to date, we've had 18.28 inches, 0.64 inches above normal. Last year featured even more precipitation.

Temperatures this month have run 4 degrees higher than normal, despite the recent cool spell. But spring has featured fairly normal temperatures and rainfall, Mr. Hendricks said.

Tomorrow and Sunday, temperatures will be in the 70s, which is slightly cooler than normal, with a 30 to 40 percent chance of showers and thunderstorms.

But the big buzz remains: Will bugs rule the summer season and plague people with bites that itch, hurt and sometimes infect?

"Who knows?" Mr. Todaro said. "Mother Nature is funny. Every season is different and that's why it's never boring."