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Worried about beetles in pine trees?By Randy Buhler CSU Cooperative Extension agent, agronomy, Logan County Colorado A recent visitor to our Extension office expressed worry about beetles attacking his pine trees planted in a windbreak. All of the major media's attention to mountain pine beetle infestations has no doubt caused others to worry as well. However, are we not way out here on the plains, far away from any mountain beetles? Yes, we are, but there are other beetles that can attack pine and spruce trees out here on the plains. They are known as Ips beetles or engraver beetles. Ips beetles have a similar lifecycle to the mountain pine beetle. There are eleven species of Ips beetles. Ips is the genus designation for these bark-invading insects. They burrow underneath the outer bark of pine trees and leave patterns of chewed out tunnels engraved into the wood of the tree. The patterns of tunnels can girdle the tree and kill part, or all, of the infested tree. A typical symptom is dead branches with reddish-brown needles appearing. It is often limited to just the top or a single branch. You may notice that the foliage fades from green to yellow-green then brown. With successive generations of beetles, more and more of the tree may die until the entire tree is dead. When you look closely at the bark of the affected limbs, you may notice small round holes peppering the surface. The holes are small in diameter, under one-eighth inch, which matches the beetles size of one-eighth to three-eighths inch in length. These holes mean the adults have emerged and headed for another branch or tree. Woodpeckers often will remove the tree bark in an effort to get to the Ips beetle larvae, pupae and adults. The ragged holes the woodpeckers leave are a clue to look closer at your trees for signs of these beetles. Woodpeckers are a natural control for the Ips beetle, but cannot stop a heavy population of beetles from damaging your trees. Inspect your high value ornamental and shelterbelt, pine and spruce trees prior to spring warm up. The beetles become active when the air temperature is averaging 50 to 60 degrees Fahrenheit. That can be anytime between late February and late November in northeastern Colorado. Insecticides for application as drenching bark sprays are available to homeowners. Formulations of permethrin or carbaryl will provide up to three months protection when properly applied. Some formulations of chlorpyrifos remain labeled for this use. You must apply the spray prior to the adults emerging from the branches. The adult beetles are out for only a day or two before they burrow into fresh bark and start a new life cycle. There can be several generations each year, depending on the species and weather conditions. A spray applied in early spring and again three months later can provide protection from re-infestation. Be sure to follow directions for application as a bark spray for treating Ips beetles or bark beetles. We have a good publication by Whitney Cranshaw and David Leatherman titled Ips Beetles, Fact Sheet 5.558 available at the Extension office. The fact sheet is also available online at www.ext.colostate.edu. Select the Horticulture button, then click on Insect Fact Sheets, then click on Home & Garden and scroll down to 5.558, Ips beetles. Click on PDF to get a print out copy. Any pine or spruce tree is subject to attack from Ips beetles. Junipers and cedars escape this pest. Broadleaf trees are not on their menu. Avoid firewood that has bark attached and that comes from the mountains. These beetles can be easily spread from an infested area to an uninfested area in a load of firewood. Chipping those pruned branches that are infested can kill the beetles and larvae. 3/3/08 Date: 2/27/08
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