Question
I have noticed that the bark of my maple tree, 3 yo, is splitting and there are little white worms in the trunk.  What shall I do?

Also, I have a Japanese lilac tree that has less leaves and did not bloom this year.  Many of the branches have no leaves.  Any thoughts?

Answer
The white "worms" are the larvae form of an insect called  a borer. I would spray the trunk with an insecticide called Merit, this will kill the borers in the trunk. Also borers attack trees under stress so I would fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good.
Sorry I know little about Lilac.