Police found several dead yellow jackets in the house and are investigating whether Eggleston had an allergic reaction to the stings. Police said Eggleston was found shortly after 7 p.m. by his 24-year-old daughter.

Family members told police the victim had no known allergies to insect stings, and investigators are waiting for toxicology test results to confirm their suspicion that the stings killed him. If they're right, police said, Eggleston's death would be the first sting-related death in memory in the county.

"Stings are common this summer," said Prince William County police spokeswoman Kim D. Chinn. "A death is a rarity."

Yellow jackets usually nest in the ground or at ground level, in fallen logs or in tree stumps. In populated areas, they can be found under stairs and in fence posts, brick walls and piles of debris.

Wasp or bee stings can produce a range of reactions, depending on the victim. The least serious is a swelling about the size of a quarter. Some people suffer extremely painful swelling that spreads as much as 12 inches from the wound. Severely allergic people can go into what is known as anaphylactic shock, which can kill.

"When that happens, all the tissue in the trachea and bronchial tubes swell up and you can't breathe," said James Werner, a family practitioner in Manassas who said his insect-sting caseload has doubled since last summer. "Bee stings cause more deaths than lightning, more deaths than shark attacks. I have patients for whom it's a real concern."