I have wanted a serviceberry tree for several years, and finally we bought one this past April and had it planted professionally by the nursery. It was near the end of blossoming when we got it, but produced a lot of very tasty berries later on which the birds enjoyed immensely.
About three weeks ago, I noticed that something was eating the leaves at an alarming rate. The person at the nursery looked at my pictures and thought it might be some kind of caterpillar, though I hadn’t seen anything on the tree at all. She suggested we spray the tree with Neem oil, a topical, organic pesticide. So with some reservations, we sprayed the tree twice, one week apart, but without any effect. Today, the pest expert at the nursery called us and said he thinks it might be a leaf roller wasp, a native wasp that cuts out semi-circles and then rolls her larvae up in them, along with some pollen, to pupate. A larger tree isn’t affected very much by the leaf damage, but it can be significant in a smaller tree like ours. The expert isn’t entirely sure of his diagnosis, so I will be showing him more pictures, and in the meantime we will just hope for the best.
My serviceberry tree is showing some significant damage
It’s even more defoliated now!
A close-up of the half-moon cuts in the leaves
Bare twigs with only the central leaf veins remaining!
FROM WEEDS TO BEES 
I’m glad he didn’t recommend a systemic pesticide. Let’s hope the tree can recover.
Robin
He did mention that he would not recommend a systemic treatment because that would mean using a neonicotinoid with all the problems that would cause. I told him I wouldn’t even consider it and he seemed pleased that I knew about them. The tree’s terminal buds all seem to still be alive, so we shall see what happens!
I had been wondering about Neem oil myself, whether it is as safe as advertised. Actually I have been thinking just recently I would ask Robin what she knows about that. It has always worked well for me when my plants started showing leaf damage (presumably from insects), just perks them right back up. I am sorry to hear your service berry tree is not doing well; I put one in last year also, and it has not grown as much as it was supposed to but looks okay. I think it may need to be trimmed to grow as a tree rather than a bush, and my usual tree trimmers don’t seem to know anything about that.
Bonnie