Question
I have a 25 year old pin oak with some gall growth.  This is the first time I have noticed the squirrels are chewing off small branches to the ground and chewing all the old gall growths off  and leaving little pieces on the ground too.  Are squirrels a good natural way of getting rid of some of the galls?

Answer
Well one of the treatments is to cut the galls off and IF the squirrels are doing this they are destroying the grubs in the galls. Since you say the galls are chewed on I would think it was squirrels. There is an insect called the twig girdler that will cut the twigs off---they lay their eggs in the twig and cut them and the eggs hatch on the ground and complete the life cycle in the ground. They do not chew the galls.