Some New and Little-Known Insects of Economic Importance on Range Grasses1

Abstract

Several insect pests of range grass seed production, not previously reported, are described. About 60 species of grasses were observed. A new genus and species of Chloropidae caused major damage to developing seed of alkali sacaton, Sporobolus airoides Torr., and sand dropseed, S. cryptandrus (Torr.). Two species of Contarinia , one C. wattsi Gagne, which attacks the developing seed of little bluestem, Andropogon scoparius (Michx.), and the other, C. halliicola Gagne, which attacks sand bluestem, A. halli (Hack.), destroyed more than 20% of the seed. Haplotthrips haplophilus Hood damage to alkali sacaton varied greatly from plant to plant; on some plants nearly all seed were destroyed. Anaphothrips zeae Moulton and grass thrips, A. obscurus (Muller), damaged the foliage, but not the seed, of several cool-season grasses, especially Agropyron spp. and Dactylis glomrata (L.). Wheat head armyworm, Faronla diffusa (Walker), was found on many grasses but damaged only sand bluestem appreciably. Wheat curl mite, Aceria tulipae (Keifer), destroyed nearly all the seed of 9 accessions of spike muhly, Muhlenbergia werighti Vasey, but one wns undnmaged and apparently immune. The feeding of this mite so enlarges the palea and the encapsulated, mummified flower parts that the florets resemble a gall. Stem-boring Hymenoptera, principally Eurytomocharis , are common in a limited range of grass species and infest up to 30% of the stems of some. Their influence on seed production has not been established. E. sporoboli Bugbee was predominant in alkali sacaton but was also reared from sand dropseed; blue grama, Bouletoua gracilis (H.B.K.) ; and sideoats grama, B. curtipendula (Michx.). E. erogrostidis Howard was found most frequently in sideoats grama but was reared from spike muhly and galleta, Hilaria jamesi (Torr.). E. planitiae Bugbee was most common in blue grama but was reared from sideoats grama. E. pascorum Bugbee was most often reared from sideoats grama bill it was reared also from blue grama and galleta. Harmotila sp. was reared in small numbers only from spike muhly. Parasitic Hymenoptera reared from grasses infested wild Eurytomocharis and Harmonia are listed.