Those are leafcutter bees and they are building there nest with the rose leaf material. I just let them alone here.
I've included information on them below.

Here is a link that might be useful: Leafcutter bee

Those are leafcutter bees. They're harmless, valuable pollinators.

Once a year, when they build their nests, they take some circular pieces of leaf. No big deal, and they are fascinating to watch.

The LAST thing you want to do is kill them! Leave them alone, and when they're done nest-building, they will no longer damage leaves.

Jeri

Yep once they have finished they wouldn't take anymore. Pollinators are very important and I know they are seeing drops in bee populations. I have always found them neat to watch.

They only like the softer leaves. If you have any roses with a leathery type leaf, you may only see a partial cut on one leaf.

If the bee truly bothers you, follow it to the nest and hose it down. The bee may move on.

They decimated my roses this year, but once I found out what they were I just let them bee. ;)

I'm getting lots of new leaves now and no more damage, so just the bottom leaves look like swiss cheese. So many bees are dying that I don't want to harm a single pollinator ... I have tons of wasps here and don't even bother them.

Darlene

Thanks for all the replies. Jim thanks for the link, exactly what the bee's and leaves look like, interesting. Practically every leave was cut out on the 3 rose bushes I have. Doesn't look like it would be too good for the plant though. I guess I should in the words of the Beetles..."just let it bee"?
Thanks for the replies, Dewyd.

What would cause the bees to devour the rose itself (rather than the leaves)? Is there something in the petals they like? And are they cutter bees or some other kind?

they use the pieces of leaf for nesting material for their eggs. they do not eat the leaves.

Leaf cutter bees don't (at least not to my experience) touch blooms. Mrs.wiggley, perhaps start a new thread to talk about the problem that you are seeing. Sounds more like Japanese beetle damage.

I have 5 new tree roses on my back deck and I noticed all 5 of them have half eaten holes on the leaves. I've read here it's the cutter bees doing the damage. I sprayed something on the trees for insects so now I'm worried I may have hurt the bee and given it poison to take back to the nest. Any answers for me?

>> what I wouldn't give to have a leaf cutter this year. ... VERY few bees. I plant a few things to bring them in

Some sources say they can be enticed to stay around by supplying housing like one would do for mason bees.