naturesnippets Introduction to the wonders of nature

A small dead branch, about 7 feet long, had fallen out of dawn redwood tree in my backyard. It had been dead long enough for all the bark to fall off.

This exposed signs of bark beetle activities underneath.

Bark beetles are teeny insects that bore through the bark, and the larvae feed in the layer of wood between the bark and the limb. Most of them overwinter as mature larvae. They then pupate in the spring. The adults either remain in the tree, or bore out of it and fly to new trees.

The particular species in the picture above, the female makes a channel in the wood with niches on each side. She then lays an egg in each niche. The larvae eat the wood out from the main tunnel.

Some species of bark beetles spend their whole life inside the tree. I wonder if this one did that? The larger hole and the shape of the chamber seem to indicate it did.

We can follow the life and growth of this bark beetle by the chamber (shown in this and the four following pictures).

The tunnel gradually widens as it curves along.

A zig and a zag as the larva continues.

It seemed to grow rapidly and maybe change its eating habits somewhat (with the quickly widening of the chamber).

With the bark missing I can only speculate that the beetle bored out through the bark and either stayed in this tree or flew to another one.

This shows some of the bark beetle activity near the base of the small limb.

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Then I remembered another bark beetle tunnel … in a piece of petrified wood I found years ago in an outcrop on the side of a road.

It’s not the best preservation, but it does have the identifying details. The underside of the rock shows the thin bark of the wood.