the bark on the tree is being eating by something, my husband thinks it is a animal,I am not sure. The tree is about 3 years old , what can we do to save it from this?

There are two types of locust growing in the midwest. Both have numerous problems so I will comment on the two more common ones (which inludes animals). The black locust and the honeylocust are the two locust. Blach locust has small thorns like a rose plant. If you have a honeylocust with thorns the thorns are about two to three inches long.. Both are prone to canker diseases that kill the bark. On the black locust the dead bark often falls off. (Sometimes confused with animal damage.) If the area is small enough the tree will continue growing while it rots away. On a honey locust, the cankers tend to kill the bark and the tree without the bark falling off for a long time. Rabbits may eat the bark off both these trees while they are young and the bark is thin. If the rabbit eat all the way around the tree is girdled and the top dies. Another animal that may chew on the bark is a skunk looking for borers right under the bark. The final animal is a vole which usually only feeds on the bark of young trees when there is tall grass surrounding the trunk or when there is snow three or more inches deep around the trunk. Look for teeth marks (if animal). Voles teeth are narrow so the teeth marks are about as wide as a tooth pick. Rabbits and skunks have wider teeth. their teeth are about as wide as a wooden pencil. Keep rabbits and skunks away from trunk by using chicken wire (out about two inches) that is at least three high. for the vole use 1/4 inch mesh hardware cloth anchored well to the ground or keep tall grass cut and snows removed for at least three feet out from trunk.