Spruce Beetle: A Rising Concern in Colorado's Forests

 

Spruce beetle, a bark beetle native to Colorado’s forests, is on the rise. In 2016, about 350,000 acres had an active infestation with 136,000 acres newly impacted. This made spruce beetle the most widespread and destructive forest pest in the state. Here’s what you need to know about spruce beetle:

  • The primary host is high elevation Engelmann spruce trees. Colorado blue spruce are only occasionally attacked.
  • The worst infestations are currently in the southwest part of the state.
  • Outbreaks tend to be associated with over-mature stands of trees or in areas where a large number of trees have been blown over.
  • Larvae feed under the bark creating girdling wounds that cut the flow of water within the tree and lead to tree death.
  • We have seen pockets of spruce beetle activity in the Roaring Fork and Vail Valleys. Spruce trees in the Vail Valley, many of which are stressed due to pine needle scale infestations, are certainly more prone to attack. However, at this time, we still consider spruce beetle to be a minor insect pest locally.
  • Most spruce trees in the Roaring Fork and Vail Valleys face little risk from spruce beetle at this time. The exception is if you have stressed spruce trees, large Engelmann spruce on your property or if you border a native spruce forest.