WHAT ARE THE EARLY SIGNS THAT BARK BEETLES HAVE COLONIZED A TREE?
Needle discoloration is the primary early sign of colonization by bark beetles. Needles fade from dark green to pale green to straw yellow to a rusty red color. The progression from green to red can occur as quickly as a couple of months or as long as several months. Other signs are pitch tubes, boring dust, and galleries (tunnels under the bark). Pitch (resin) is the tree’s only natural defense against bark beetles. Beetles colonizing relatively healthy trees will usually create pitch tubes where the beetle entered the tree. If the tube is connected with a tunnel that continues into the bark, then that beetle successfully entered the tree. Fine boring dust is sometimes visible and caused by bark beetles chewing the bark to enter the tree. During initial colonization, the boring dust is bright red. To inspect for galleries, you can remove a portion of the bark with an axe. This should be done only after the tree appears to be dead. Galleries should be visible under the bark and may con
