Bag worms eat leaves of many trees. Hanging from the branches are bags shaped like a carrot. Larva makes a bag that covers its whole body. As the larva grows they add to the bag. They are anywhere from 1 inch to 3 inches long. The bags are made up of interwoven pieces of dead foliage, silk and twigs. When the bag is cut open a blackish tan caterpillar or a yellowish grub like insect may be inside. The mother bag worm can lay eggs anywhere from 500 to 1,000 eggs. The eggs live in the mother’s bag all through the winter. These bag worms may stunt a deciduous tree or kill evergreens.