Sorry - no idea...but commenting to bump the post to the top...

it looks like a firefly (actually a type of beetle)

the adults dont eat leaves feed on nectar

the larvae eat slugs.....

those holes in your leaves look like slug damage from baby slugs

I'm with Jim. Unless you actually see the beetle eating on a leaf I'd consider it an innocent bystander. Slugs are atop the suspect list.

tj

Slugs and snails. I couldn't get over the suction when I pried a baby snail off of Summer Breeze earlier this morning. The other little guy hadn't settled down yet, easier to pick off. (It seems that snails make smaller holes i've noticed.)

Thanks folks for your insights. I have only seen two of the black bugs so do not think that they are the culprits. I think the baby slugs are the nasty things eating the plants. I will treat it as such. Hosta blessings to everyone!