If you have spruce or pine trees, check them now. If the central leader is totally brown and flagged (drooping over like a shepherd’s crook) as well as perhaps some of the branches in the first whorl, it’s likely you have this pest.
Don’t panic because this pest can be controlled; in addition, you can fix the tree with a little bit of work so that it has a new central leader and continues to grow upright.
At this point, the larvae are close to completing their feeding. They overwinter as adults in the leaf litter around the tree. They emerge and lay their eggs in the central leader around April. The larvae hatch and begin feeding down the central leader.
Right now, the larvae are very close to pupating, after which the adults will emerge and hang out for a while before overwintering. The adults do little damage and are not considered important.
The first thing to do at this time is to cut out dead wood. Before you do this, read on further.
It’s possible that you can run your hand down the trunk and actually find the larvae when making pruning cuts. Squish them dead if you do! This helps to reduce the problem next season.
Don’t worry about insecticides right now. Worry about getting your pine or spruce tree back into shape. Before you cut off all of the dead wood, take a look at the next living whorl and select a branch long enough that can be trained to become the new central leader.
Take the longest or best branch in this next whorl and straighten it up to become dominant over the lateral branches. To do this, you need something to anchor it to.
Leave the dead central leader in place and remove the dead lateral branches. Use the remaining dead trunk as the anchor. Use sheets, plastic plant support tape, or some other material that won’t cut into the branch and gently tie the longest branch to the dead trunk.
Next year, when the new central leader takes off, you can cut the rest of the dead wood out.
This fall, apply a pesticide that contains the active ingredient imidacloprid around the base of the tree according to directions. This is absorbed into the tree and will be in its system before the larvae begin feeding next year.
This is a damaging insect and needs to be managed in order to keep your trees looking their best.
Pam Corle-Bennett is an Ohio State University Extension horticulture educator and the state master gardener volunteer coordinator.
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