Sap-Sucking Insects, Gall Formers and Mites
FIELD GUIDE TO INSECTS AND DISEASES OF ARIZONA AND NEW MEXICO FORESTS
Pinyon Spindlegall Midge
Pinyonia edulicola (Gangé)

Host:  Piñon

Figure 78. Figure 78. Gall on piñon caused by pinyon spindle gall midge.

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.

Figure 79. Figure 79. Orange-colored maggots of pinyon spindle gall midge.

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, 24