In larger infestations, caterpillars can be controlled with foliar sprays of azadirachtin, Bacillus thuringiensis var. Consult the labels for dosage rates and safety precautions. Lilac borer, Podosesia syringae . The first evidence of damage is sap mixed with fine frass oozing from small irregularly shaped holes on infested branches. Rough swellings develop on infested limbs, branches may wilt and die outward from feeding sites, and branches may become weakened enough to break where larvae were tunneling.
Pheromone traps are available to monitor moth activity.
Winter is passed in the larval stage under the bark. For control, prune infested stems. Carbaryl or chlorpyrifos, which are among the compounds registered for control of this pest in Connecticut, may be applied to trunks and major limbs to kill the adults during their period of flight activity. Consult the label for dosage rates and safety precautions.