What are the little green caterpillars found on an oak tree?


This year, we had a huge amount of little green caterpillars in the oak tree in our backyard. If you sat under the tree for any length of time, you would have caterpillars all over you, because they were dropping down on little silks. The caterpillars seem to be gone now, but they ate a lot of holes in the oak leaves and they look really ratty. Is there anything we can do about this? Will it grow new leaves this year? Is the tree in any danger?


Jonathan Foster, Special Project Assistant 

I reached out to UMaine Cooperative Extension entomologist Charlie Armstrong to try to identify your problem (there are several possible culprits, based on your information). His reply, in part:

“The spring and fall cankerworms aren’t really very green, so I don’t think so with regards to “cankerworm,” but they are a type of looper, yes, in the Geometridae family.  I would say they are either the Bruce Spanworm or else equally likely, Winter Moth.  Those two species are both very green in color and superficially look the same.

Winter moth has been bad in southern Maine this year so I bet it’s that one.”