Two types of wood borers that usually attack softwood house logs are commonly known as Flat-headed or Round-headed Wood Borers. The adult of the round-headed borer (larva) are commonly called Pine Sawyers or Long-Horned Beetles.
These borers lay eggs in small pits in the bark and the eggs hatch in 2 to 4 weeks. Larva feed for a few weeks just under the bark, boring into the log. These borers feed deeper into the wood as it dries.
The life cycle is usually 1 to 2 years, but larvae may feed for at least 6 years when wood moisture is low. Powderpost beetles are small wood-boring beetles that measure 1/8" to 5/16" long. These beetles attack sapwood of ring-porous and diffuse-porous hardwoods that have a high content of starch. These beetles also reinfest milled lumber. Tell-tale signs of this pest are small piles of fine brown flour-like wood material.
Powderpost beetles seem to prefer unheated areas; thus their infestation seems to be more of a problem in seasonal homes. As a preventative measure, the use of borates (see PeneTreat) and coating wood with a finish helps to make infestation more difficult. As a spot treatment insecticides such as Bug Juice (just mix with a little stain) can be injected into holes with a syringe.