Question
I live in northern British Columbia, Smithers, and have a question about my maple tree.
For the past couple of years, my tree has been developing what looks like warts on the leaves.  They are reddish and seem to be hollow with no noticeable bugs in the wart. The leaf gets covered and most of the leaves are effected.
The tree seems healthy apart from that.
Any idea what it might be and can anything be done to get rid of the warts?

Thanks for your help.
Frank

Answer
These are leaf gall insects and they will not harm the tree. The tiny insect (wasp) lays its eggs on the leaf and secretes a chemical that causes the leaf to grow over the egg. The insect does not feed on the leaf and cause no real problem except for the spot on the leaf. No control is needed since they do not effect the health of the tree.