That does look like a slug. I have had a bright green worm eat on mine but apparently rose chaffers do more damage. What ever was done was some time ago given the dried edges of the cut areas. Nothing to be done now but look at the other plants for damage and hope what ever did the damage is not there next year.
No, it's not a slug...not sure exactly what you're looking at, but there are 3 damaged buds in the picture, and you could just be looking at one of the buds. We have tons of slugs here, and I've never seen them on peonies. I don't think they bother them too much.
I have seen some cutworms on them before. Some of the stems were cut clean off! I have a huge problem with them! I'm just trying to confirm if this damage is actually from them - or could it be something else?
I've used a product called Thuricide on them. One nursery said it was an organic, "safe" treatment for cutworms. Anyone heard of this? One of my problems here in W.Oregon is that you have to apply it after rain - which is like EVERY day here, in the spring time.
I looked up your chemical it is a BT that kills caterpillars. Which means it should kill all caterpillars including butterfly and moth ones that we need to pollinate our crops. You can use it if you want but this is really one of my pet peaves having lost a collection of woodland plants that I had rescued.
You should always read and research the chemicals that you use and do not rely on what anyone tells you. You may have to think beyond your use to additional damage that the substance may cause before using it.
Now I will step off my soap box.
I still believe that the damage was done some time ago and doing anything now is a waste of time and effort.
I wondered about the caterpillar/butterfly thing, which is why I haven't used that spray a whole lot. Didn't want to kill the good guys. I had done some research on thuricide, and even found it approved on an organic site, but I don't want it to kill the butterflies too. I will look more into that. Thanks for the thoughts - don't even mind the soap box. I have many of mine too. :)
I'll probably just resort back to my old method of wearing my silly headlamp and hand picking off cutworms, after dark. They're so disgusting!
I read somewhere that ants covering peony buds are there to protect the bloom from predators and such. They come for the sugar exuded by the bud and stay for protection. Is it possible your ecosystem is a little off? Are you under a tree that's drips sap, tree stuff and worms?
What we called cutworms I believe were actually Japanese beetle grubs in an earlier stage.
Since I have a lot of trouble with red lily beetles, I use a product used on pets to keep them from biting their treated areas or tails. It is extremely bitter tasting. As a bonus, it is so bitter that none of the predators like it. You can purchase "Bitter Apple," "Bitter Yuck" or "Phooey" (meant for horses). If you use it, wear gloves and a mask because it is in fact very bitter to humans too. Unfortunately it needs to be reapplied when it rains.
I also use a product called a deer repellant, which is made with essential oils and smells of oil of clove. It has an oil base and is diluted with water appropriately or it will burn the leaves. However, it does not rinse off in the rain.
The lilies used to be eaten at the stem, and the sprays seem to help there also.