<P> Oak apple or oak gall is the common name for a large , round , vaguely apple - like gall commonly found on many species of oak . Oak apples range in size from 2 to 4 centimetres ( 1 to 2 in ) in diameter and are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae . The adult female wasp lays single eggs in developing leaf buds . The wasp larvae feed on the gall tissue resulting from their secretions . Considerable confusion exists in the general `` literature '' between the oak apple and the oak marble gall . The oak marble is frequently called the oak apple due to the superficial resemblance and the preponderance of the oak marble gall in the wild . Other galls found on oak trees include the oak artichoke gall and the acorn cup gall , but each of these has its own distinctive form . </P>
<P> Oak apple or oak gall is the common name for a large , round , vaguely apple - like gall commonly found on many species of oak . Oak apples range in size from 2 to 4 centimetres ( 1 to 2 in ) in diameter and are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae . The adult female wasp lays single eggs in developing leaf buds . The wasp larvae feed on the gall tissue resulting from their secretions . Considerable confusion exists in the general `` literature '' between the oak apple and the oak marble gall . The oak marble is frequently called the oak apple due to the superficial resemblance and the preponderance of the oak marble gall in the wild . Other galls found on oak trees include the oak artichoke gall and the acorn cup gall , but each of these has its own distinctive form . </P>
what are the balls that grow on oak trees
what are the balls that grow on oak trees
Oak apple or oak gall
Oak apple or oak gall