Wild Wednesday - Pine Sawyer Beetle

By Andy Ames

Smile for the camera! The Spotted pine sawyer is one of the most easily recognizable beetles in the Estes Valley. It’s long antennae and powerful jaws set it apart. As pine beetles, they are often attributed to killing trees. In reality, Pine sawyers mostly feed on already dead or dying trees, often following fires and mountain pine beetle outbreaks. After mating, adult females bore a small hole in the bark of a pine tree and deposited a single egg. This is repeated many times. Once hatched, the larvae initially tunnel just below the bark creating grooves and accumulations of sawdust as they go. During this stage Pine sawyer larvae may actually consume the smaller Mountain pine beetle larvae they encounter. Later the larvae drill deeper into the wood to feed on the sapwood and heartwood of the tree. Nearing full size, the larvae return to the surface to form a pupae just under the bark. After about a week the newly formed adult cuts its way out and now feeds on needles and tender bark of pines. While there may be some localized die back, this foraging usually doesn’t harm native trees.

Pine sawyer beetles can inadvertently spread Pine wilt disease, however. Pine wilt is caused by tiny pine wood nematodes that can spread rapidly and cause the sudden death of a tree. Pine sawyer larvae can pick up these nematodes by feeding on an infected tree and then, as adults, transmit them to a new tree. This mostly affects non-native trees but has infected some local Ponderosas recently.

Pine sawyer beetles are easily recognizable by their long antennae. Female’s antennae are usually about the length of their body, male’s twice as long.

With their powerful jaws, Pine sawyers are considered “wood borers”, able to drill deep into the heart of a tree as larvae.

Female Spotted pine sawyer beetle.

Somehow this individual lost the lower part of its rear leg.

Much like the adults, pine sawyer larvae possess strong jaws to chew through bark and wood.