Grasshopper Damage on Short-Grass Rangeland of the San Carlos Apache Indian Reservation, Arizona2

Abstract

Over a 3-year period there was great variation in vegetative ground cover, and stands of perennial grass were more uniform and stable than those of annual grass or forbs. Blue grama and alfilaria were dominant, and perennial grasses were the most valuable and dependable forage plants. Important grasshoppers were the migratory grasshopper ( Melanoplus bilituratus (Walker)) Aulocara elliotti (Thos.), and M. cuneatus (Gurney). All the species fed on a wide variety of grasses and forbs, but bilituratus and cunealus showed a greater preference for forbs than did elliotti. Grasshopper populations ranged from 9 to 27 per square yard. Average damage was 23% to perennial grass, 26% to forbs, and 30% to annual grass. Total damage and unit-area damage per grasshopper were greatest in July, and unit-area damage per grasshopper was greater to annual grass and forbs than to perennial grass. Damage to perennial grass was greatest where the vegetation was sparse and the grasshopper population high, while the highest unit-area damage per grasshopper occurred where the vegetation was sparse and the grasshopper population moderate to light. The perennial grass ground cover was highest where elliotti was dominant.