RANGELAND GRASSHOPPERS (ORTHOPTERA, ACRIDIDAE) ASSOCIATED WITH MESQUITE AND JUNIPER HABITATS IN THE TEXAS ROLLING PLAINS

Density, species composition, and spatial distribution of grasshoppers and biomass and species composition of herbaceous plants in 2 rangela nd habitats, honey mesquite, Prosopis glandulosa Torrey, and redberry juniper, Juniperus pinchott Sudworth, were quantified in die Texas Rol ling Plains in 1992 and 1993. Grasshoppers were sampled weekly from ea rly May to late September, and vegetation was sampled 3 times (May, Ju ly, and September). Grasshopper density was significantly greater in t he mesquite habitat than in the juniper habitat for both;ears, with an average of 6.38 and 5.50 grasshoppers per square meter in mesquite ha bitat and 0.86 and 0.33 grasshoppers per square meter in juniper habit at in 1992 and 1993, respectively. Grasshopper species composition var ied with sampling year and with die habitat, with significantly greate r species diversity in mesquite habitat compared with that in the juni per habitat. Of the 37 species of grasshoppers captured during the 2-y r study, 3 species in the mesquite habitat, Hesperotettix speciosus (S cudder), Nesperotettix viridis (Thomas), and Syrbula admirabilis Uhler , and 2 species in the juniper habitat, Ageneotettix deorum (Scudder) and S. admirabilis, comprised approximate to 50% of the adult grasshop pers collected. Analysis of dispersion patterns of grasshoppers in 1-m (2) transects showed that the grasshoppers exhibit a random spatial pa ttern in both habitats. Average herbaceous biomass for both years was greater in the mesquite (mean = 3,435 kg/h) than in the juniper (mean = 793 kg/h) habitat, with greater grass than forb biomass in both habi tats. Grasshopper abundance and species composition in rangeland mesqu ite and juniper habitats appear to be related with the herbaceous plan t community structure in those habitats.