Tabanidae (Diptera) of Texas. VII. Comparisons of upland and lowland tabanid populations in southeast Texas

It is reported in this further paper in a series [see RAE/B 65, 2969, etc.] that the tabanid faunas of adjacent upland and lowland ecosystems on the Navasota River of south-central Texas produced 17 370 and 12 840 flies, respectively, through daily collections at each site in March-September 1975 with one Gressitt trap using carbon dioxide [see 66, 1009]. These catches included 26 species at each locality; 21 species were common to both. However, based on collection data from 4 previous years, the lowland fauna was probably more diverse and produced 8 more resident species and more of the numerous species in greater numbers. At the upland and lowland locales, the genus Tabanus included 65 and 73% of the species, respectively, and 96 and 92% of the specimens. Tabanus subsimilis subsimilis Bellardi and T. sulcifrons Macq. were among the 3 most abundant dominants at each community, whereas 4 spp. were found in large numbers in one community and nearly absent in the other (many T. quaesitus Stone in uplands; T. fuscicostatus Hine, T. lineola F. and Hybomitra lasiophthalma (Macq.) in lowlands). The upland ecosystem produced 26% more material than the lowland one, probably because floods in August-September drowned large numbers of pupae of T. subsimilis subsimilis and of other species.