Ips Beetle – A Killer of Pine and Spruce Trees

Ips beetles are a frequent problem in Colorado, including here in the Denver foothills where they can kill whole forests in a single season. They’re especially problematic during periods of prolonged drought like we’re having at the moment.

What is an Ips Beetle?

Ips beetle. Image Darren Blackford, USDA Forest Service, Bugwood.org

The Ips beetle is a bark beetle that feeds on the phloem of trees. Sometimes called “engraver beetles” because of the way they tunnel or engrave a gallery of paths under the bark, Ips beetles will eventually kill the trees they infest.

They attack spruce and pine trees, including lodgepole and ponderosa pines, and are particularly attracted to stressed or dying trees. The beetles are also attracted to freshly cut or broken wood, such as from pruning or logging, and wind or snow damage.

Ips beetles are small (only 1/8 to 3/8 inch long), reddish-brown to black and have spines and a depressed area at the rear end of the body.

There are 11 different species of Ips beetle that are native to Colorado, and all are capable of killing pine and spruce trees.

While the Ips beetle is similar to the mountain pine beetle, there are some important differences that affect the timing and method of control. For that reason, it’s important to properly identify which beetle is affecting your trees before trying to manage it.

How To Tell If Your Trees Are Infested With Ips Beetles

It’s not always easy to determine what’s affecting your pine and spruce trees, but here are some general symptoms to look for.

  • Parts of the tree discolor and die in spring, summer or early fall. It can happen very quickly and can affect just the top of larger trees or the whole tree.
  • Reddish-brown boring dust in bark crevices and at the base of the tree
  • “Y” or “H” shaped galleries under the bark (you may need to peel off some bark to see this). The galleries won’t have sawdust in them.
  • Woodpeckers feeding on the trunk or larger branches (they’re a common predator of the Ips beetle)
  • Small round holes in the bark. You’ll usually see these after the beetles have already done their damage and exited the tree.

When Do Ips Beetles Attack Trees?

Although the exact timing depends on temperature (daytime temperatures need to be above 50°F before the beetles emerge), in our area of the Front Range the Ips beetle can start flying in early March. They’ll continue to attack trees until as late as November, but it’s the early season attacks that generally cause the most damage.

How to Protect Trees From Ips Beetles

There are two ways to protect your pine and spruce trees – practices that lessen the risk of infestation, and insecticides that help prevent Ips beetle attacks.

Preventive Actions

  • Maintain the health and vigor of your trees, including providing plenty of water during dry spells
  • Be careful when thinning or pruning trees – injured trees attract Ips beetles
  • Don’t place freshly cut branches or logs, or stack unseasoned firewood, near living trees as it will attract the beetles
  • Promptly cut down infested trees and remove infested logs from your property and have them debarked or chipped
  • Keep a close eye on your spruce and pine trees for any signed of infestation

Insecticide Treatment

  • Treatment is only effective if the tree has not yet been attacked. It cannot be applied after the tree shows signs of infestation.
  • There are several effective products registered in Colorado to treat Ips beetles
  • Spraying should be done before the beetles emerge. We usually start in late February or early March (depending on weather).
  • Treatment is only effective if the entire tree is sprayed. Because the upper part of the tree is difficult to reach, spraying should only be done by certified and licensed applicators who have the proper equipment to do the job properly.
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