Wood Borers

Wood Borers
Roundhead borers, Cerambydidae
Flathead borers, Buprestidae

Hosts:  Conifers and hardwoods

Figure 143. Adult longhorned beetles (adults of roundheaded wood borers). Note that antennae are longer than the length of the body.Symptoms/Signs:  Larvae are found under the bark of dead and dying trees. These galleries are usually wider than bark beetle galleries and vary in diameter as the larva grows, in contrast to the egg galleries of bark beetles which have a uniform diameter throughout. Roundheaded borer galleries are packed with a coarse boring material while flatheaded borer galleries are packed with fine boring dust. In many species, larvae complete their development in the wood so tunnels extend into sapwood and sometimes the heartwood. Adults emerge through large emergence holes in the bark.

Adult roundheaded borers are medium to large sized, oblong to cylindrical insects. The antennae are often longer than the body, giving them the name “longhorned beetles.” Larvae are relatively large, particularly when fully developed, white, cylindrically shaped grubs. The heads are slightly larger in diameter than the body.

Figure 144. Larva of flatheaded wood borer. Note that their flattened heads are usually broader than the body.Adult flatheaded borers are medium to large sized, flattened, compact, and often brightly colored beetles. Larvae have a very distinctive shape. The first body segment behind the head is much broader than the following body segments and has horny plates on the top and bottom.

Effects:  These insects primarily attack weakened, dead or dying trees. A few species attack and kill apparently healthy trees, such as the western cedar borer on junipers and Agrilus species on Populus. They often attack trees already infested with bark beetles and sometimes compete with them. Larval mines penetrate both the cambial region as well as the wood, sometimes mining it extensively. They are important in the process of nutrient cycling by assisting in breaking down woody material.

Reference:  23

Figure 145. Adult metallic wood borer (flatheaded wood borer). Note that antennae are shorter than the body.