A few holes is no threat to the tree. Even a lot of holes, while aesthetically unsightly, will not harm the tree. The insect causing holes may be a caterpillar, beetle, or grasshopper. If you can identify the culprit then the best control can be prescribed. If you don't see the culprits during the day then try going out at nite with a flashlight. Caterpillars are safely controlled with B.t. Beetles may need a product containing spinosad or something stronger. If you find the culprit please submit another question to the website and I'll provide a better directed reply.
Thanks for the question. Please stop in again soon!
Q&A Library Searching Tips