Ants on trees in NJ are usually there because they are
a) Are nesting in the wood. So, they could be carpenter ants. This is not likely in a cherry tree as they usually nest in different species where there is a significant amount of dead wood. These ants prefer to excavate inside the dead wood and not the living wood
b) They are getting sugar from the plant feeding insects on the cherry. Aphids suck juices from the leaves and a byproduct is honeydew. They excrete this and the ants consume it, fueling in their colony. They will remember the tree and source of aphids, and recruit other ants to that place.
Ants will make you aphid problem much worse as they protect the aphids against natural enemies like ladybug larvae.
Look to see where they ants are going. If the problem is aphids the ants will be going underneath the leaves where the aphids are.
The solution is spraying the aphids with either water or soapy water. A high pressure is best. You want to wash the aphids off and then the ants will stop coming
see also this post https://www.plantvillage.com/posts/15...
do some observations and tell us what is going on. Also a photo please