Carpenter bees are large, black and yellow bees frequently seen in spring hovering around the eaves of a house or the underside of a deck or porch rail. The carpenter bee is so-called because of its habit of excavating six-inch to one-foot tunnels in wood with its strong jaws.  Wooden decks, overhangs and other exposed wood on houses are prime targets. Painted and treated woods are less preferred, but they are by no means immune to attack. Unpainted or stained cedar, cypress and redwood shingles and siding are also attacked despite their pest-resistant reputations. A tell-tale trace of coarse sawdust is often found on the surface beneath the hole. Carpenter bees overwinter as adults, often inside old nest tunnels. They emerge in April and May. Males can be distinguished from females by a whitish spot on the front of the face. The males do not have stingers, but they are territorial and will harass other bees and people who venture near their protected areas. Females can sting, but rarely do so unless confined in your hand or are highly agitated.