The pupal skin sticking out of the side ofthe tree is often one of the first signs lilac ash borer has infested a tree or shrub.  Photo provided by:  Whitney Cranshaw, Colorado State University, Bugwood.org

Mating pair of lilac/ash borers (Sessidae; a type of moth).  Photo provided by:  Whitney Cranshaw, Colorado State University, Bugwood.org

Larvae (pictured) borer through the wood as they feed.  Photo provided by:  David Cappaert, Michigan State University, Bugwood.org