Question
We have a magnolia tree that suddenly (and for the first time that we've noticed) has hundreds (or at least dozens) of small brown caterpillars congregating on the crook of the branches and seem to be making small holes in the trunk.  What are they and what should I do?

Answer
I think it is the Omnivorous Looper Caterpillars. They will congregate in the crook of the tree and then migrate to the leaves for feeding. The easiest way to control them is to spray the caterpillars with an insecticide. I would use liquid Sevin. Check with your local nursery/garden type store for an insecticide for caterpillars on trees. They may say use BT which is a good one but will require the insect eat the Bt. I would use a contact type insecticide for this problem.