...adults emerged from shoots of white spruce in May. A few days following emergence, eggs appeared at the base of needles and under bud scales of new shoots. Upon hatching, larvae bored directly into the shoots and formed individual chambers, some very close together. Swellings were noticeable in about 10 days. Infested shoots swelled to about twice their normal diameter and some became curled or twisted..

Swollen twig ... "Mayetiola" piceae (Felt)

Eggs are laid at the base of new needles. The larvae are always in individual chambers...Severe infestations cause twigs to bend and twist. Many needles drop off, and the twigs are sometimes killed. Felt (1940) indicated that Mayetiola tsugae Felt caused this damage, but that species is known from a specimen caught in flight and is not the same as "M." piceae [see Gagné & Graney (2014) for the rationale for applying "tsugae" anyway to the "M." piceae gall-former.] Hosts: P. glauca, P. rubens...