The Yellow Headed Spruce Sawfly (Pikonema alaskensis) is native to North America. Mature larvae are about 20 mm (three quarters of an inch) long. They look like hairless green caterpillars with a series of darker stripes running along the body. They have a distinctive dark yellowish head.
This pest attacks spruce trees, especially young, open-grown trees. The larvae eat all the new needles before moving onto older ones. Feeding damage starts near the top of a tree and moves downward.
If the spruce trees attacked are small and few in number, this pest can be controlled by hand picking and destroying the larvae when they first appear mid to late June. Young larvae may also be controlled by hosing them off with a strong jet of water. Insecticide can be applied mid to late June to protect larger spruce trees under attack.