This well-known oak tree parasite is a caterpillar that devours the leaves, until it gathers to form a nest that looks like a spider web.
Solution to treat against oak processionary
There is practically no available effective anti-parasite treatment.
To preserve the surrounding trees, just cut off the branches where the nests are and destroy them.
Also read our pages on fighting caterpillars.
Smart tip about oak processionary
Take great care when cutting the branches off, because hairs from the hairy caterpillars are extremely itchy, not only for you but also for your dogs, cats, and any other animal living in your house!