Pupae develop deep within the wood and are seldom seen. Note the decay, often associated with trees in which the larvae survive to maturity. The sugar maple borer has a two-year life cycle. Most eggs are laid in midsummer in roughened bark locations-in cracks, under bark scales, or around wounds. Upon hatching, the larva makes a meandering mine beneath the bark.
Mining continues until early fall when it excavates a shallow cell in the sapwood.
Here it spends the winter. The following spring, the larva resumes mining, etching a deep groove in the sapwood. The mine partially encircles the bole or branch as it spirals upward. In the tunnel's far end, the larva forms a chamber for overwintering. Before spring pupation, the larva chews a hole to the outside through which it will emerge as an adult in June or July.