Habitats of larval Tabanidae (Diptera) in South Texas

The habitats and interspecific associations of 12 species of tabanids in south-eastern Texas are described from studies in which various mechanical methods were used for extracting larvae from soil samples, and 0.002% emulsions of pyrethrins and resmethrin were applied at 1 US gal/yd2 to cause larvae to emerge from the soil. The Navasota River floodplain was the most prolific source, producing 298 larvae in 28 soil treatments with pyrethroid emulsions in the period from 29 March to 12 August 1976. Five species were represented in the samples there: Tabanus atratus F. (41.8%), T. proximus Wlk. (36.8%), T. subsimilis subsimilis Bellardi (14.4%), T. trimaculatus P. de B. (5.6%) and T. lineola F. (1.4%). This total of 5 species was less than one-fifth of the 26 species taken as adults by Gressitt traps in 1975. Conversely, T. atratus, the most abundant species in larval collections, comprised only 0.1% of the adults collected in 1975. Larvae of one or 2 species predominated at any given site and time, and low indices of affinity suggested that no specific association existed between larvae of any 2 species found together.