Q.What kind of tree is this and why is it wilty?
The edges of the leaves are turning brown and it looks like there are insect bites on them, some leaves are turning yellow and dropping. It’s also been extremely dry as windy here (western Colorado).
It's hard to get a positive ID of the tree without flowers or seeds, but from the leaves it appears to be a poplar, like aspen or cottonwood.
Leaf margins turning brown, leaves yellowing and dropping, can surely be related to the extremely dry and windy conditions you describe = water deficit (drought stress). Give the tree an immediate deep watering and then once a week through the summer hot dry period.
Insect pest activity can be secondary to the drought stress. From the photo the feeding doesn't appear severe.