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Be A Beetle Detective

Ranger Rick Bark Beetle story from May 2010

Ancient writing? "Modern art"? What are the strange patterns you see under the bark of dead trees?

Believe it or not, they're tunnels made by bark beetles (see small photo below). Mother beetles lay eggs in tunnels they make underneath tree bark. When the eggs hatch, the larvae (young beetles) begin munching on the wood. As they feed, they carve out more tunnels, each leading away from the main one.

When the bark is on the tree, you can't see the beetles' artwork. But when the tree dies and the bark falls off, the hidden tunnels are revealed, as you can see below.
There are hundreds of different kinds of bark beetles, and they live in forests almost everywhere. Some kinds cause big problems, invading in huge numbers and killing many trees. Others are just doing their job in a healthy forest. Most likely, some are hard at work in a tree near you. Now that you know their secret, here's what to look for:

Galleries. That's what the patterns are called. The mother beetle lays her eggs in a wide center tunnel. When the larvae hatch, they make their own tunnels.
Expanding Tunnels. As each larva eats, its body grows. That means the tunnel it chews grows larger and larger, too. See if you can spot this pattern.
Exit Holes. Once a larva has grown into an adult, it leaves the tree. If the bark is still in place, you may be able to see holes where grown-up beetles escaped.

--KATE HOFMANN

Download the PDF of Undercover Artists from the 2010 issue of Ranger Rick® magazine.