The head, throax, and a portion of the abdomen are chestnut red with narrow, black margins. Damage -Lilac borers tunne into the main stems, causing the plant to wilt during hot weather. Infested shrubs appear unhealthy, the stems breaking off rather easily.
Infested areas appear swollen and cracked because the sapwood is also destroyed.
Numerous holes are visible in heavily infested stock, and frass is usually abundant. Moreover, the wounds caused by the lilac borer allow a wood-destroying fungus, Polyporus vericolor, to enter, producing additional damage. Adults emerge in August and September to mate, and the females lay their eggs on the rough bark or wounds of lilac and privet. As soon as they hatch, the tiny worms bore into the bark. Contact is maintained with the outside, and frass is expelled through the opening.