STEWARTSTOWN, Pa. -- While most people are watching television after a hard day's work, Clay Benton is tucking away his gun and badge for the night. By day, the Baltimore County police officer chases two-legged culprits, and by night, his prey has wings and stingers.

Mr. Benton, 32, catches wasps, yellow jackets, yellow hornets and white-faced hornets.

The tall Pennsylvania native has been rounding up stinging insects since 1977, when he was helping his father tend their honeybee farm.

These days, he's catching hornets and wasps to sell by the pound to a pharmaceutical company. The resulting venom extract is used to make a vaccine for people allergic to stings.

"It's a matter of who kills who first," said Mr. Benton, a Garrison Precinct patrolman who was nursing a right hand swollen from three stings the night before. "Some nights I win; some nights I lose."

Mr. Benton does his collecting in the dark because "bees aren't as active at night." He collects only certain species, and then only if they haven't been tainted by insecticides.

In a way, Mr. Benton's night job allows him to follow in the footsteps of his father, Allen W. Benton, a retired entomologist who began researching venom extract in the 1960s. Now, the younger Mr. Benton is the first step in a process that often starts in a hole in the ground and ends up saving lives.

The hornets and wasps he collects are shipped frozen to Vespa Laboratories Inc. in Spring Mills, Pa., which was started in 1977 by Allen Benton and is one of two pharmaceutical companies in the country that use the pure venom extract to produce the first stage of the vaccine.

In a summer, Vespa employs 30 to several hundred collectors, the number depending on what species of wasp, bee or hornet is in demand.

Some people are allergic to bees, but not to wasps or hornets; some are allergic to more than one or all. In the worst case, they would need a different vaccine for each allergy.

So, as the reddish streaks of sunlight give way to the blue-gray of the evening sky, Mr. Benton cruises the roads of southern Pennsylvania and Baltimore County, preparing to battle the little pollinators.

Sometimes, people who call him to get rid of the insects can't resist watching his flashlight beam from afar as he searches the ground for a yellow jacket nest. That was the case on a recent night at the rural York County home of Kenny Pizlo and his family, who had contacted Mr. Benton after two yellow jacket attacks.

"People only call me when someone gets nailed," Mr. Benton said, pointing to a small hole in the ground. "Poor junior is playing ball and he gets stung . . . or someone's working in a garden and they get attacked. It's a great deal, because I get the bees and they get rid of their bees for free."

Covered by jeans, a long-sleeved shirt, gloves and a veil, Mr. Benton armed himself with a long shovel, a bucket of dirt, a tiny flashlight and a funnel connected to a plastic one-gallon milk jug.

Clamping the flashlight in his teeth, he placed the funnel and milk jug trap over the hole and secured it with dirt. The light went off, and within seconds the thumping of his shovel broke the silence.

"I bang on the ground until they get mad and fly out of the hole into my trap," he said. In most cases, the trap works well, but not tonight.

As he clicked the flashlight back on, a swarm of yellow jackets, escaping from the trap, dive-bombed him.

"I think you better make a run for it," Mr. Benton said calmly to Kenny Pizlo and his two curious sons.

He told them to go to the side of the house away from the light, because yellow jackets can't see in the dark, but one of the boys went screaming into the house after a yellow jacket stinger found its mark.

"Like I said, sometimes you win, sometimes you lose," said Mr. Benton, apologizing to the family for the attack and promising to come back to finish the job. "I lost big tonight; that was a huge nest." He got only 150 yellow jackets from it.

Checking his clothing for lingerers, he packed his gear and drove toward the next site -- only to be stung on the way by a yellow jacket that had hidden in his equipment. His hand now had four stings.

Is it worth all this?

Mr. Benton says so.

To get away from pressures of his "intriguing day job," he says, he looks forward to the nightly escapades.

This is from a man who got a bachelor's degree in administrative justice from Pennsylvania State University, then decided to pursue "a much more exciting" career as a police officer.

Reluctant to disclose how much he makes catching hornets and wasps, he said it is enough to keep him out catching the insects despite the hundreds of stings he has received in the 17 years he has been doing it.

"It's a nice summer job," he said. But it is more than a summer job.

His role is part of a larger effort in which allergists and entomologists created a venom vaccine that proved to be 98 percent effective in treating allergies to insect stings, said Miles W. Guralnick, president of Vespa.

"These collectors come from all walks of life," Mr. Guralnick said, "lawyers, doctors, teachers. . . . They all have one thing in common: They seem to not have a fear of being stung, where most people would be scared to death. Their work makes our work possible."

Vespa removes the insects' tiny, football-shaped venom sacs and partially purifies the venom, a six-week process. That material is then sold to other pharmaceutical companies, which transform the extract into an injectable drug.

Twenty years ago, Clay Benton's father connected with doctors from John Hopkins Hospital.

In the early 1970s, the elder Mr. Benton, then teaching at Penn State, came up with techniques for collecting large amounts of honeybee venom.

Working with doctors including Martin D. Valentine, a Hopkins allergist who specializes in venom research, Allen Benton helped develop the sting-allergy vaccine used today.

In building up resistance levels, patients undergo vaccine injections once a week for 12 to 16 weeks, with booster shots for up to five years.

To start treatments, a victim must be diagnosed with allergies to stings, and not just have the normal swelling and pain associated with a sting, Mr. Guralnick said.

People extremely sensitive to stings often have reactions serious enough to require emergency room treatment. Those reactions include hives or welts, swelling of the throat that impairs breathing, loss of consciousness or going into shock.

Nationally, about 40 people a year die because of stings. Hopkins treats thousands of victims yearly, Dr. Valentine said.

"In the late summer and early fall, you have a lot of yellow jackets that get increasingly hungry," he said. "They compete for our food outside, so more people get stung.

For Lou Hardesty, 11 weeks of venom shots could mean the difference between life and death. Since a near-fatal sting in May, the Howard County 911 dispatcher has relied on injections of yellow jacket venom.

Mr. Hardesty, 48, of Winfield in Carroll County, has been stung three times in three years by yellow jackets. Each time, the sting has left the 6-foot-4, 380-pound man unconscious. The third time was the worst.

"They had a hard time bringing me back to consciousness," Mr. Hardesty said. "My blood pressure dropped to almost zero. It's amazing, because I'm a big man and I'm not allergic to anything, but a little teeny bee will put me down in a heartbeat.

"I'm pretty confident that these shots are going to help me though."