Rose, if you can tell us what part of the world you are gardening in, that will give a hint as to the ID of the tree in your third picture.
As Ken said, it looks like it might be a Crepe Myrtle but it's hard to tell until it has leaves and flowers.
As far as the bug goes, if you can just back up and get a better picture of both the bugs and the plant that will help. Some plants are hosts to certain types of bug, or are attractive to them. Also are they feeding, laying eggs, sucking nectar or what? More info and better pics will help.
