Archive for March 2nd, 2010

When walking in the woods on the weekend, I followed the sound of tapping to its source and observed this Piliated Woodpecker (Dryocopus pileatus) at work. I was only able to get one quick photo, taken at a distance, before the woodpecker took off and quickly disappeared into the forest.

There are plenty of excavations in area woodlands that give evidence of the presence of Piliated Woodpeckers. When I stopped to look at the hole shown below, I noticed there were lots of tiny holes around the woodpecker’s work.

These tiny holes aren’t the work of any bird. Rather, they are the emergence holes of bark beetles. Bark beetles (family Scolytidae)begin their life cycle when the female beetle mates and digs an egg tunnel in the tree surface, depositing her eggs at either side of her tunnel. The larvae hatch and begin eating their own tunnels through the wood under the bark. When they are ready to pupate, each larva hollows out a chamber where it forms a cocoon and transforms into an adult. The new adults emerge through the bark and fly away to a new tree to begin the cycle again.

You can find bark beetle engravings on trees that have lost their bark quite readily. The tunnels often have a central point from which short tunnels radiate or fork out, or the pattern of the tunnels may be irregular. The tunnels I found were often zigzagging. The pattern of the tunnel isn’t distinctive to any one species. However, different species of bark beetles prefer certain types of trees and particular areas of that tree, such as upper branches or the trunk.

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