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The Life and Times of the Humble Bark Beetle

By Jennifer Correa-Kruegel, Warren County Naturalist

January 29, 2026

carvings left in log from bark beetle — The bark beetle's feeding habits leave behind a distinctive marking. Photo by Jennifer Correa-Kruegel.

Bark beetles are so-called not because of any canine-like noise that they make, but rather that they feed on the inner bark of trees. There are various different species, each type of bark bettle having some of their own unique characteristics. Bark beetles are of the family Scolytidae, and there are quite a few different varieties.

Some aspects that are similar throughout this family are that the female excavates an egg tunnel in the wood surface placing eggs in small cavities. When the larvae hatch, they eat the wood, leaving their own mazes known as “larval mines.”

As the larvae grow, so do the tunnels, finally resting in a chamber, just big enough to allow the insect to morph in spring and surface as adults in early summer after overwintering within the bark of the tree.

Depending on the species, there may be one or more broods throughout the summer, with the last brood overwintering.

Some types of bark beetle species are happy to consume downed or dead trees. Others, however, may prefer to feast on the internal bark of living trees. While they are usually a part of the natural cycle of forest life, they sometimes can be considered a harmful pest when they consume —and kill—large numbers of their favorite trees.

No matter where you look, Searching for evidence of bark beetles in winter can be a fun activity. You may not be able to glimpse the diminutive insect itself, but their tunnels alone tell an incredible story. Some ways to make bark beetle hunting even more entertaining is to bring along a magnifying glass or a plain piece of paper and crayon to create a make your own bark beetle rubbing.

While public opinion of the bark beetle remains somewhat mixed, most people can agree that each pattern left behind in the wake of their meal is a mesmerizing work of natural art.

Fun Facts About the Bark Beetle:

Bark beetle eggs are laid in tunnels under the wood surface.
Bark beetle larvae create tunnels through the wood known as “larval mines.”
The “larval mines” can be visible on down trees where the exterior bark has peeled off.
A plain piece of paper and the long side of a crayon can make a unique rubbing art.

Jennifer Correa-Kruegel, Warren County Naturalist

Jennifer has a Masters in Parks and Resource Management from Slippery Rock University. She worked as a Park Naturalist for Hunterdon County Park System from 2003-2006 and then at the NJSOC full-time from 2006 - 2020, starting as the Program Coordinator and evolving to an Environmental Educator. Jen is a New Jersey native and has lived in Warren County with her family since 2004. She is excited to be offering programs to this community she has grown to love.