Presence of spindle-like swellings at the base of needles
that are about 1 cm long with tiny, orange maggots inside.
Biology: Adults lay eggs on needles in late
June and early July. Larvae hatch soon afterward and mine into the
current year’s needles near the base. The plant forms a gall
around the feeding larvae. Each gall contains 5 to 40 small, orange
legless maggots. The larvae overwinter in the galls and pupate in
This is a common forest insect that rarely causes serious
damage. However, heavy infestations in urban settings cause serious
defoliation when needles drop prematurely.