FORTUNE — When a forest fire flared up near Manton, Calif., late this summer, Lionel Bonanno jumped into a fire truck and raced to the evacuation zone. He closed up windows and sprayed fire retardant around dozens of homes. It’s likely that, in the coming months, he’ll have to do this again: Fire season now extends to November in much of the West. While Bonanno is a trained firefighter, he isn’t a public servant. If he sees a burning home, he is not legally bound to take action.
He is a “wildfire-mitigation specialist,” employed by the home insurer Chartis, a division of AIG (AIG). In the past four years half-a-dozen insurers have begun sending out similar private firefighting crews in an attempt to stem multimillion-dollar losses from flames in the West. Last year insurers lost $855 million to catastrophic wildfires. In 2000 they lost $183 million.
More luxury homes are being built in the fire-prone West: The U.S. Forest Service estimates that about 60% of the homes erected from 1990 to 2000 were built in forested areas near public lands.
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Chartis offers the wildfire protection service to its 30,000 Western U.S. policyholders, each of whom may pay up to $20,000 a year for their policies. The insurer created its own internal fire department in 2010, after contracting for two years with a third-party company. One such firm, Wildfire Defense Systems, a 12-year-old forest service contractor in Bozeman, Mont., dispatches its 150 on-call firefighters to protect homes and to teach homeowners fire protection, showing them which tree branches to trim or wood piles to move.
Chartis now employs 17 people who monitor fire alerts, wind, and weather. This was a busy summer for the company’s 14 firefighters, who took their seven trucks to 12 fires throughout the West. Chartis lost 17 homes in the catastrophic California fires in 2007; it has lost none to wildfires since.
The Chubb Corp., (CB) which uses Wildfire Defense Systems, recently added evacuation services, setting policyholders up in hotels and helping evacuate their pets. Up next: teams dispatched during hurricanes. Scott Spencer, a senior vice president at Chubb, says, “We say, ‘Here is what you do, and how to do it.'”
This story is from the September 24, 2012 issue of Fortune.
Editor’s note: A previous version of this story incorrectly stated that Chartis hired Wildfire Defense Systems to handle its wildfire protection services. In fact, Chartis hired a different third-party company before creating its own internal fire department in 2010.