Pine tree crown neeldes yellow? Brownish to reddish? Holes in the tree trunk? Pitch tubes present? Find out more about pine tree bark beetles and what to do.
What is it?
The dendroctonus species of bark beetles feed on pine trees, although they will also occasionally choose to infest spruce or larch trees as well. Pine trees can be weakened by bark beetles, or infestation may become so severe as to kill off the entire tree.
What does it look like?
Pine bark beetles may have infested your tree if you note that the tree has needles around the crown which have yellowed, or gradually gone from yellow to a brownish or reddish orange. You may also note small holes within the body of the tree trunk or small masses of tube-shaped pitch around those holes. The beetles spend much of their time underneath cover of the bark so are rarely seen, and are most often noted by evidence of damage to the pine tree.
How does it manifest?
Pine bark beetles will attack the middle and upper portions of the body of the trunk of the pine tree. It is here where the adult bark beetles burrow and create tunnels in the meat of the tree. It also where the females locate and lay their eggs for hatching. Once larvae hatch, they begin tunneling through the bark and feeding on it. It is through this process that they then pupate within the tunnels and emerge from the small holes as mature, adult bark beetles. Having a few beetles within the tree will only weaken it due to the holes and tunnels created by this process. However, eventually this process of breeding and feeding may result in a large enough beetle population to kill off the tree. The more pitch tubes you find, the larger population of bark beetles you have.
What can you do about it?
You must remove the severely infested tree as soon as possible. If there is evidence of an extreme amount of bark beetles, the pine tree will have been sufficiently weakened that it cannot survive. If there are only a moderate number of pitch tubes, you may be able to smash tubes with a heavy rubber mallet - this is less damaging to the tree than metal. If you smash with the mallet near the tunnels you may very well squash the insect beneath in their galleries. Then spray the trunk of the tree with lindane containing insecticide. Further return the tree to health by watering it thoroughly every 4 to 6 weeks, and diligently ever 4 weeks in drier months. You want to avoid injury to the trunk and tree roots, so be careful with the mallet. Beetles are also attracted by pine trimmings and cut pine wood near the trunks of trees, so removal of such piles with help prevent drawing them to healthy pines.
