Those may not be eating your rose petals, but may be predatory insects eating whatever is eating the petals. It looks like some of the leaves have been eaten, too.

They look like something from the assassin bug group--there are many different ones. But they are insect eaters, so probably they are after what is eating your rose petals rather than doing the damage themselves.

I also thought it might be a leaf-foot bug, but those have a more shield-like body.

Looks an awful lot like a baby grasshopper or katydid.

Try fork-tailed bush katydid maybe? Compare the immature images to your guys. (The adults look different from the super small ones like yours would be.)

It's an immature katydid I think and they do love eating rosebuds and ruin as many as they can. I go out with a flashlight and a pair of scissors a little after sunset and cut their heads off. Alternative is taking the scissors out early on a cool morning b(ecause they don't move much when it is still very cool). Snip, snip.

That is very halloweeny, Hoovb! Can't you just squish 'em? Or shake them into a bowl of soapy water? :)

I'm guessing that Amanda is not going to return to let us know where on the planet she lives.

I'm thinking that this is an immature Palmetto Conehead Katydid or something similar. Absolutely not one of the predatory Hemipterans but an Orthopteran.