Big Silver Maple with something boring into the base

Asked October 12, 2016, 1:10 PM EDT

We have a large, healthy mature Maple tree and recently noticed about 2 cups of 'saw dust' at the base in one location. The dust is in the form of short fiber strands , not really saw dust. Upon inspection I saw a medium sized black ant retreat into the hole which was close to ground level, but not sure if he was the cause or just exploring.
1) who is the likely culprit
2) how should this be treated
3) is the tree sick if it getting attacked?
Thanks.....Bruce in Golden

Jefferson County Colorado trees and shrubs

4 Responses

Hi Bruce,

In order to correctly identify the problem, we’d like some pictures and have more questions.

Could you please provide a picture of the whole tree and it’s environment (a “big picture view”) as well as some close-ups of the sawdust and the bore hole? How big is the hole and can you tell if it’s round or oval? Is there only one bore hole or more? Is the hole on the south side of tree? Can you see any ‘tunneling’ activity? (loopy trails in the bark). Does the tree have any sunscald? Maples in Colorado are very susceptible to this and the affected area is then in turn is susceptible to insect activity.

Do you see any other insects in the area besides the ant? If so, a picture of the insect would be greatly beneficial. It’s possible the culprit is a carpenter worm as they create sawdust when boring but we need more info to confirm as there are a few other possibilities. Your tree is probably very healthy but it has a defect that the boring insect has exploited. The major concern is in determining how much of the structural wood has been compromised. Managing wood boring insects in structural wood is a challenge do to the removal of many insecticides from the market. Here is a link to our Fact Sheet on wood borers:

The dust is in a single location on the east side of the trunk, right at ground level. I can't see the actual hole because it is up inside the scar. The ants seem to be scavengers more than culprits. Here are some pic's as requested. Thanks for your help.

Hello Curtis,

I replied to your initial response with some photos, but I'm not sure if you were notified of the new information. It posted as if from an anonymous guest. Let me know that you received this response and whether I should resend the photos.


Dear Bruce,

The saw dust and presence of the large ants confirms the ants are the culprits and are using your maple tree as a nesting site. I am including a link to our fact sheet on Carpenter ants for your review.

It is highly likely that in Heartwood of your tree has begun to decay.