Insect

I found some trees and bushes have been eaten by spider in and out campus.First, the spider wrap a part of trees,and we'll see a big cobweb in the trees. Then , the leaves became brown and dry,then the leaves disapeeared. After that, there will be other cobwebs in trees around there and leaves disappear.
I googled and knew that some spiders done eaten plants , but this phenomenna should be controlled.