Thomas J. Hegarty drives around the Vineyard in his Dukes County pickup truck as though he could drive right out to the edge of the world. He holds up the peace sign to nearly every car he passes, or at least calls out the window to say hello.

He’s a man about town, but the former carpenter, contractor and Lampost bartender with the trademark Ray-Ban sunglasses and sometimes coarse sense of humor, has another side too. Mr. Hegarty is celebrating his 10th year as the director of the county integrated pest management program.

Yes, celebrating.

You may know him as the rat man, T.J., the skunk man, or to squeamish homeowners the man who will happily take care of your rodent problem, but his newest title is mosquito man.

T.J. Hegarty is leading a mosquito study on the Vineyard that tests pools of skeeters for West Nile virus and eastern equine encephalitis, better known as Triple E. He’s setting up traps in Edgartown, West Tisbury, Chilmark, Aquinnah and Tisbury once a week for 10 weeks in the hope of learning more about the mosquito population here. (Oak Bluffs voted not to participate in the integrated pest management program this year and is not included in the study.)

After they are trapped, the mosquitoes are frozen in a sterilized tube and transported in a cooler to Woods Hole. At that point they are picked up by Gabrielle Sakolsky, assistant superintendent and entomologist for the Cape Cod Mosquito Control Project, who picks them up and sends them to a laboratory for testing in Boston.

There is no cause for worry — there have been no cases of either virus found this year, and the last time West Nile was found on the Vineyard dates back to 2008 when a bird was found in Edgartown with the virus.

But Mr. Hegarty says it’s not so much a question of if, but when the virus will come in human form. The hot spots he chose for testing are near high populations of children and will provide the county with a better idea of mosquito activity in each town. They include the New Westside Cemetery in Edgartown, the Chilmark School, the Aquinnah Library, the West Tisbury Library, and John Hoft Road.

“If we can collect most of the data where there’s a history of children around, that’s great as far as I’m concerned,” he says during a recent collection day. “We’re also an international tourist destination and it behooves us to study it.”

The testing begins with a special compote of what Mr. Hegarty calls Dukes County tea — old leaves, pine needles, dirt and hay that he soaks in water for a week to ferment.

“It needs to be nice and ripe,” he says with a grin, bending over the buckets of fermented water, the strong smell reminiscent of old water from a flower vase. “It needs to foam like a good latte when you pour it. That’s what you’re looking for.”

Don’t try this at home: Collecting Mosquito Larvae. — Ray Ewing

The stronger the smell the better — female mosquitoes are more likely to lay eggs at the top of the water if the water is, as Mr. Hegarty says, nice and ripe.

After the “tea” is steeped, Mr. Hegarty is ready to set out traps. Last week he loaded up his truck with six buckets of the special concoction and headed to the Edgartown cemetery.

“Cemeteries are good places to trap mosquitoes because of the stagnant water in the vases,” he explains. “This is one of my favorite spots. Mosquitoes love to lay their eggs here.”

Mr. Hegarty sets up the gravid trap — a basin bottom filled with the foul water with a special fan that sucks up the mosquitoes and catches them in a bag. He deliberately chose five locations away from water so as not to catch saltwater-loving mosquitoes. The study is geared toward the mosquito genus Culvex pipiens, otherwise known as the northern house mosquito. This is the mosquito that is a vector for diseases such as West Nile and Triple E.

In a recent collection he captured one mosquito in Tisbury, nine in Edgartown, nine in Chilmark, 19 in Aquinnah and 30 in West Tisbury.

“A gold mine,” he calls the West Tisbury site.

His skills dealing with pests date back to 24 years ago, when one summer he trapped 76 skunks at his West Tisbury home. But he needed a problem animal control license (PAC) from the state Division of Fisheries and Wildlife in order to continue keeping the skunks out of his garden, and subsequently took a required class where he learned about the biology of the animals — and something about himself.

“There was also a social profiling component where they tried to weed out people who would treat the animals indifferently,” Mr. Hegarty recalls. “You really have to learn. You have to have respect for them [the animals], and you learn from them when you go out.”

Mr. Hegarty has been trapping skunks, raccoons and setting up bait traps for rats (of which he sees about 5,000 a year on the Vineyard) for the county for the past 10 years, and he’s as salty and energized as he was the first day he started the job. It may be hard for the average person to think much of his job, but Mr. Hegarty says he’s had fun along the way.

That includes the giant inflatable rat which he brings to the Martha’s Vineyard Agricultural Fair and the Fourth of July parade in Edgartown every year. Mr. Hegarty raised $5,000 in private donations to buy the larger-than-life rat eight years ago.

“It really showed this incredible support from the community and it was fun to realize there were like-minded people with the same sense of humor,” says Mr. Hegarty, who now donates the rat for Vineyard charity auctions. “But the best part of all this is the people I get to meet along the way.”