After hatching out, the young borers dig down to the roots and begin feeding on the bark. They move through the soil from one root to another, feeding on the surfaces of small roots and eventually enter the wood of larger roots, which they hollow, girdle or sever. Toward the end of the 1800's it was deemed second in importance only to the codling moth as an apple pest, and there was some speculation that it might cause the demise of N.Y.'s apple industry. However, because of the adult's susceptibility to pesticides applied against other pests in most commercial orchards, it is found today mainly in abandoned, wild or unsprayed plantings. Frequently, several larvae may be found in a single tree, which is enough to completely girdle a young tree.
Infested trees have a sickly appearance, producing sparse, pale-colored foliage.
Continued yearly attacks can kill the tree or weaken so that it is broken off by the wind. Trees suffering from sun scald are regarded as being particularly subject to attack. Points of larval activity are difficult to locate, as scarcely any castings are thrown out, although white, frothy sap may be seen oozing from cracks in the bark. Young trees are sometimes chewed off just below the surface and their root systems devoured. Established trees may have one or two roots left near the surface that keep them alive until blown over by the wind.