I'll see if I can't get a better picture of the bug.

Is that hops in the background? Both hops and birch are susceptible to Japanese beetle damage.

Not Japanese beetle. Blueocean, a much improved image is required for an identification.

My point was that the unknown bug isn't necessarily the cause of the leaf damage. JB's could be responsible for some (or most) of the feeding damage.

It will do better next year, don't worry about leaf damage now.

Excellent point, Dave.

Logan Johnson (of CH&G), some people simply want to know the identity of an unknown creature.

blueocean indicated no concern about the minor damage to the tree. He/she simply has a curious mind.

Blue, I hope that you can supply more images. There are insect larvae that do disguise themselves with excrement, detritus, and/or shed exoskeletons.

ok, I am no professional when it comes to insects. All I do is kill them when they eat my plants LOL.

I'm surprised that either slugs or ants would be eating a birch tree. Are you sure about that? Aphids love birch and it's possible the ants are enjoying the honeydew harvest, not eating the leaves.

Thank you for your interest everyone. I can't seem to get a better picture of the bug. My cell and tablet won't focus on something that small and that close to the lens. Whatever it is looks to be dead and half-decaying, so I won't worry about it.

I can't say for sure that the slugs or ants are eating the tree, but there are certainly a lot of them on and around it. Plus since the slugs love my young willows, I figured the birch would be popular as well.

Birch are a favorite host to different types of scale insects and asphids, both of which produce a sugary sweet excrement called honeydew. Many types of ants feed ravenously on the honeydew, which might explain their large numbers on your birch.

Unfortunately, some scale species are very difficult for a novice to identify and since they suck plant saps rather than chew holes in leaves, their damage may go unnoticed.

Large numbers of ants would be a warning sign for me, blue. If I were you, I would find someone to inspect the stems and small branches of your young birch for scale insects.

Or you could take some stem pictures for me, in focus.

No treatment recommendations unless the pests are actually identified.

Ants may be feeding off of the honeydew released by the scale.

Umm... CH&G did you read the previous post? Or mine two posts above?

Well, I did now.