Since that unfortunate introduction, the disease and the barkbeetles have worked as a deadly team. In return, the dying trees provide an excellent habitat for large colonies of barkbeetles. The European elm barkbeetle, slightly larger than the native species prefers to build its galleries with the central egg tunnel running with the wood s grain. Smaller side tunnels made by the newly hatched larvae radiate out from the central one. 21. Galleries of the native elm bark beetle are oriented across the grain and are usually forked.
Pines are subject to attack by several species of bark beetles.
Some infest only the smaller branches, others only the trunk. The beetles are very similar in appearance, but each species vary considerably in size and each has a distinctive gallery. As with borers, bark beetle control is mainly preventative. Maintaining trees in good condition is very important since bark beetles prefer weak, unthrifty trees. Once infested, treatment is impractical.