The first major outbreak of this small sucking insect on sugar maple was recorded in Pennsylvania in the late 1970s. Since then, widespread damage by pear thrips has occurred on sugar maple in several Northeastern States. In 1988, approximately 1 million acres (400,000 ha) in Pennsylvania, nearly a half million acres (200,000 ha) in Vermont, and several thousand acres in Western Massachusetts were heavily infested. The consequences of this unprecedented outbreak in New England have yet to be determined, but experience in Pennsylvania indicates that even after several years of high thrips populations, sugar maple mortality is rare. During an outbreak, damage may vary substantially from tree to tree. Prolonged infestations may cause crown dieback and reduced sap volume.

This insect spends most of its life in the soil. Most of the damage occurs during a short period in the early spring when adults feed within buds. When adult populations are extremely high, there is no leaf development. Larvae also feed throughout the spring as foliage expands. Typical symptoms in light to moderate populations are whitish to yellow blotches on foliage (Fig. 51), puckered, often tattered, abnormally small leaves (Fig. 52), brown, dead areas on edges of the leaves and veins, and early leaf drop. Damage can be severe (Fig. 53) when populations are high and often resembles that caused by a late frost or strong wind. Severe injury sometimes triggers refoliation.

Pear thrips adults (Fig. 54) are extremely small (0.04 to 0.06 inch or 1 to 1.5 mm long), elongate, and dark brown. The head appears swollen, and the wings are narrow and fringed with long hairs. Larvae are yellowish to pale translucent green with conspicuous red eyes