The insect overwinters underground as a larva in a dark-brown papery cocoon encrusted with soil (Rose and Lindquist 1985).
[2] In the spring, the cocoon changes into a pupa, from which the adult emerges, mainly in May or June at about the time the spruce bud scales are sloughed off.
Any insecticide would maximize larval mortality when applied about 10 days after bud caps have been shed, but when only few trees are infested, the larvae can be picked off by hand.
A number of webspinning sawflies feed on spruce, but most of them are rare and solitary feeders, Cephalcia fascipennis being the most common.
The adults soon emerge and the female lays green cylindrical eggs singly or in end-to-end rows of 2 to 4 on the needle.
Larvae of this family typically have elongate antennae, bear a pair of jointed appendages at the posterior end, and lack abdominal legs.