What are These Worms on My Apple Tree Leaves?

I have a problem with my apple trees. They are 2-3 years old and have done well so far. This year as soon as the green started showing and the leaves started forming, I noticed something bad.

The green tips were kind of clumping together and turning brown. I discovered a tiny worm in each group of leaves, I really had to dig for them. The smaller ones are white and then some bigger ones are brownish. What could they be? Thanks.

Hardiness Zone: 4a

By mark from Norway, MI