Host:  Piñon

Symptoms/Signs:  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 the spring.

Effects:  This is a common forest insect that rarely causes serious damage. However, heavy infestations in urban settings cause serious defoliation when needles drop prematurely.

References:  8, 23