Ant colony at base of large maple


Hi I was doing some cleaning of brush away from the base of a 30 year+ maple and noticed a huge ant colony at the base of the tree. Ants were also going up the bark but did not appear to be inside the tree. I sprayed ant killer on the ground. Any other suggestions to protect the tree from ants? Thank you


Thank you for contacting Toronto Master Gardeners.

Ants, although not welcomed by everyone, are not generally harmful to trees.  It does not sound like the ants have done any damage to your tree, though you may wish to inspect them and the surrounding area to be sure.  There are various types of ants; however, and some, such as carpenter ants, may seek holes in older trees to create their nest.  Do you see any sawdust at the base of your tree?

We have received a number of questions regarding ants and trees that have been answered and may be of interest to you.  Here is one:

Please note that in Ontario there is a pesticide ban for cosmetic use.  More information about this ban can be found at:

Also, we have a couple of gardening guides available via our website that may be of interest to you: