I understand that leaf rollers eat away at the leaves and leave holes in the leaves. But do they eat away at the tops of leaves? Because it looks as though a rabbit has been eating away at the leaves on my canna.
Leaf rollers actually just eat the epidermis off the leaves, leaving them transparent. They don't eat all the way thru the leaves.
When the leafroller moth sews the leaves shut with her silken threads, the stitches will leave a row of holes as the leaves grow. But they'll be little dotted rows. They won't look like something has bitten the tops off of them.
You probably have slugs or rabbits or some other varmint nibbling on your cannas. Or even grasshoppers if you have any of those yet. Those rascals do their best to eat up my gardens each summer.
You can mix up a little cayenne pepper (just a little!!) in a spray bottle of water and spritz your plants. It will burn the varmints mouths and they'll leave your plants alone.