Food preferences of the dusky grasshopper, Encoptolophus sordidus costalis (Scudder) (Orthoptera: Acrididae)

Abstract

Crop analyses of 578 grasshoppers showed that the dusky grasshopper, Encoptolophus sordidus costalis, is primarily a grass-feeding species. All grasses are not selected randomly. About 80% of the diet consisted of Agropyron smithii, A. dasystachyum, and Carex eleocharis. The latter was eaten at a rate that was more than twice as great as that expected if feeding were proportional to the relative abundance of plant species on the study site. Therefore, this sedge is a specific preferred food plant, especially for the three early instars. Forbs were ingested very sparingly in nature (1% of diet) but 11 out of 22 species were fed upon when offered singly to starved adult grasshoppers. Non-adherence to a strictly grass diet under stress conditions is indicative of great flexibility and explains the widespread distribution of this species throughout central North America.