Differential Feeding in Relation to Local Distribution of Grasshoppers

Recent experiments show that a large percentage of North American Acrididae, which have been cage tested for food preferences, are associated with a restricted number of host plants (oligophagous). These researches demonstrate that a specific plant, or a very limited number of host plants, is essential as food for the optimum subsistence, fecundity, and longevity of each species (Criddle, '33; Isely, '38, '44). Hodge ('33) and Sanderson ('39) found that even Melanoplus differentialis (Thos.), a polyphagous pest grasshopper, has specific diet requirements. Recently Tatuber, Drake, and Decker (1945) have shown that egg production in the case of Melano plus bivitattus (Say) is strikingly correlated with different plants used as food by this economic species. In studies on the correlation between mandibular morphology and food specificity 89 North American species of Acrididae were found to be segregated into three major classes: 34 were found to be graminivorous; 37, forbivorous, and only 18 species were shown to be herbivorous, i.e., mixed feeders, either graminivorousforbivorous or forbivorous-graminivorous (Isely, '44, pp. 9 and 65). The writer is indebted to Prof. Gordon Alexander and Miss Katharine L. Maneval for reading the manuscript and making helpful suggestions. Thanks are due Mary N. Isely for assistance in all phases