Is my sugar maple sick?
It's not normal for a maple tree to lose all it's leaves in June.
There could be many factors at work, but we need more information and photos.
How old is the tree? How large? Any changes to the area? Any use of pesticides or weed killers over the root zone? How deep is the mulch? How large and how many of the holes do you see?
Are there many dead limbs in the canopy?
We'd like to see additional photos of the whole tree, including where it goes into the ground. Photos can be attached directly to this reply by using the Choose File tabs below.
Scrape branches with your fingernail and look at what color the underlying tissue is. Bend some branches. If they snap they are dead.
You can explore some issues that can cause tree decline here:
and this page helps people decide when it may be time to remove a tree: