Have had this several years on one potted Oak and now see it on others too. The one year I sprayed with lime sulfur there were none. Any other solutions? D
I used to have Pear slugs on my sour cherry tree for several years some time ago. They only chewed a few holes in some of the leaves and didn't seem to damage the tree very much; so I left them alone. After a few years they disappeared and haven't returned. If they aren't causing a lot of damage on your Oak trees, you could just ignore them. Otherwise, Google "pear slug control" for effective pesticides.
