Steve Dodge has seen the destruction termites can do from basement to attic.

And this year the cellulose-chomping critters began swarming even earlier than normal, thanks the warm weather in mid-March and April, said Dodge, one of three owners of Northern Virginia-based ProTech.

The last few days of cooling weather slowed swarming activity down, but it's coming back as the thermometer starts climbing, he said. That has caused worried homeowners to start phoning area pest control companies' offices, such as ProTech's at 1120 International Parkway in Stafford County.

And with good reason.

Termites wreak havoc to the tune of $5 billion a year as they quietly munch away at wood, wallpaper and other materials, including carpet backing. To make matters worse, the damage they leave behind is rarely covered by homeowners' insurance policies.

To keep termites at bay, the National Pest Management Alliance, a trade association based in Fairfax, recommends that homeowners get a licensed, professional exterminator to examine their property annually. Most will do this for free, and a list searchable by ZIP code is available on its website, pestworld.org, said spokeswoman Missy Henriksen.

Brian Jarvis, who manages the Orkin branch at 1002 Thomas Lane in Stafford, said his exterminators look primarily for three things:

Signs of current or past termite activity, such as the mud shelter tubes termites build as they emerge from the soil and the wings that they shed during a swarm.

Signs of termite damage, which can lurk beneath painted surfaces. Sometimes affected wood will have a layered look because termites like to fed on the spring wood between the tree rings in lumber.

Anything that might attract termites, such as firewood stacked next to the house, a patio that abuts the structure or imperfect grading that directs water toward a house instead of draining it away. (Termites prefer dark, damp environments.)

ProTech's Dodge said he has gone into crawl spaces to inspect for termite damage and found floorboards so eaten away that they were as flimsy as balsa wood, and climbed into attics where the voracious insects were gnawing away at the rafters.