Posts Tagged ‘bark beetles’

Where the Beetles Were

Obviously, the following pictures were taken at different times, when I was walking a loop around the back part of our yard.

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The limb had fallen from a large maple tree in a strong storm a few years ago.

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Bark beetles tunneled their homes under the bark.

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Most of the tunneling I’ve seen like this weren’t anywhere near as large as these.

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Obviously, I take a picture every now and then when walking by this broken limb. This picture shows how they grew. The design always catches my attention, especially if the sun’s shining.

One of Nature’s Artists

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.

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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.


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.

Bark Beetle Designs

Buffy and I walked down into the ravine and crossed the creek on my property. Rain during the night left the water in the creek slightly cloudy. A Carolina chickadee gave its “chick-a-dee-dee-dee call,” and a rufous-sided towhee repeated “wheep.”

The light was right for a change, and I could photograph the bark beetle designs on this log. Bark beetles are 1/8 inch long, and all of them feed on the layer of wood between the bark and trunk of live trees. Usually they pick trees that aren’t the healthiest.

Different bark beetle species create different tunneling patterns. Look closely at the base of all the tunneling to the wider horizontal tunnel (which would have been vertical when the tree was still alive). A female made the tunnel and then laid her eggs in niches along the side. I assumed she probably laid eggs on both sides of the tunnel, but I couldn’t tell for sure because it was on the underside of the log. It may be hard to see in the picture that there are teeny parallel tunnels coming up from the main tunnel. The tunnels grew bigger as the larvae grew. When they matured, each made an enlarged space to pupate in. The adults emerge from their pupal stage in the spring and then bore out through the bark. From there, they fly to new trees and start the cycle again. There can be 1 or 2 broods a year. Long tunnels of the same width are made by adult beetles.

 This second picture shows the tunneling pattern of a different bark beetle species. It better shows how the larvae fed out from the main tunnel. These tunnels weren’t nearly as long  as the ones above. Bark beetles use both deciduous and coniferous trees. These can be found in mature woods with downed trees.

Downed trees, in various degrees of decay, can be quite fascinating.