The term MOVING LINE ON A TREE TRUNK can be summarized as ants marching in a line on a tree trunk. Ants are small, social insects that live in colonies and are known for their organized behavior. They often form lines to move from one place to another, such as when they are foraging for food or when they are migrating. The lines of ants can be seen marching along tree trunks, which is the image this term evokes.