Biology and Impact of a Grass Bug Labops herperius Uhler in Oregon Rangeland

Abstract

Wintering eggs of a univoltive plant bug Labops hesperius Uhler in rangeland seeded to intermediate wheatgrass hatched in late March. The subsequent nymphs stayed in the litter during the day and crawled on the leaves to feed at night. Adults began to appear in late April. Females had a 2-week preoviposition period and thereafter laid diapausing eggs in dry culms of various grasses. The feeding injury produced by a density of 120 bugs per 0.96 ft2 reduced the nutritive value of intermediate wheatgrass about 18% midway through the growing season, but by the time the grass matured, the reduction due to feeding injury was only 2%. However, the impact of feeding injury on rangeland productivity varies with the time of utilization, annual rainfall, and drought. Management practices that reduce the food supply of the bugs and the availability of the straw preferred for oviposition seem a promising method of reducing the impact of feeding injury and the density of bugs.