Tree cattle are harmless
Many people are noticing small insects on trunks and branches of their trees. When disturbed, these insects move in a group and are commonly called tree cattle because of this herding habit. They are ¼ inch brownish-black insects with white markings. Some people assume that these insects will injure their trees but they are harmless. They could be considered beneficial.
Before you spray your tree to control these insects, click on the following link and read the entire article. Tree cattle are harmless