Definition of apple borer:
(n) :
Any beetle or moth that bores into the trunks of apple and other fruit trees as larvae, including:
(n) :
a roundheaded apple borer (Saperda candida, syn. Saperda bivittata)
(n) :
a flatheaded appletree borer (Chrysobothris femorata)
(n) :
a red-belted clearwing, apple clearwing moth (Synanthedon myopaeformis)
(n) :
an apple stem borer (Apriona cinerea)
(n) :
an apple twig borer (Amphicerus bicaudatus)