Using a stethoscope in a hospital is not such a strange thing to do, unless, of course, you're an exterminator, which Luis Agurto is.

Agurto, who owns the San Francisco–based pest control company Pestec, stands on a ladder and presses his stethoscope to the wall. He has the pensive look of a doctor listening for signs of arrhythmia, but Agurto has his ears peeled for a different kind of murmur: the buzz of bees. There is a printed sign on a nearby windowpane -- Do Not Open -- and beyond the glass a swarm of bees goes about the business of setting up shop in the decaying wood frame of a seventh-floor window in the city-run Laguna Honda Hospital, an aging stucco structure built in 1866.

Below Agurto, his son Carlos, 23, arms himself with a power drill. Carlos's brother, Luis Jr., 25, starts manually pumping the Foamer Simpson, a two-gallon jug with a strawlike nozzle that holds a simple mixture of sodium laureth sulfate and water -- not so different from your standard shampoo base, minus the fancy fragrance. The solution doesn't actually kill anything; bugs just want to get away from the stuff. More unseemly pests -- roaches, for example -- do get the ax, though the Agurtos do it with a human-friendly blend of boric acid and sugar. No Raid here.

Agurto's approach is to tailor each pest control solution to the specific problem at hand, and the plan on this particular day is to drill through the window frame, stuff the hive full of soap to drive the bees out, and remove the whole nest from the wall.

To Agurto, who immigrated to the United States from Nicaragua in 1979, this approach just makes sense. Every use of pesticides puts more money into the hands of chemical manufacturers. Every job he does using a little creative problem-solving, drawing on decades of experience and an understanding of entomology that would put most biologists to shame, keeps more dollars in the coffers of his small business.

Earlier, Agurto and Luis Jr. made a stop to check up on two technicians who were burying gopher traps along the Juniposera Greenway as part of Pestec's contract with the city of San Francisco. The team lays traps, waits a few hours, then goes back to remove the gophers. The alternative would be to seed the grass with poison, which is just as easily dug up and eaten by neighborhood dogs as it is by rodents. The poisoned pests get picked off by falcons and other predatory birds, which ingest the toxic chemicals along with their prey.

Pestec's annual $600,000 contract with the city accounts for 50 percent of Agurto's business. When he's not busy rodent-proofing City Hall, deploying a fleet of bike messengers to drop mosquito birth control into storm sewers, and sniffing out bedbugs with the company's highly trained beagle, Ladybug, he lectures on integrated pest management, consults for other pest control firms and institutional facilities, and quizzes Luis Jr. on ways to solve hypothetical pest control problems (he's grooming his elder son to take over the business). This year, Pestec became the first pest control company in the United States to be certified by Green Shield, a nonprofit program that endorses businesses that practice effective pest control using fewer pesticides.

The bottom line, Agurto says: "If I'm not willing to spray pesticides in my son's house where my grandkids are playing, why would I spray another person's house where their kids are playing?"