Effect of Malaise trap modifications on collections of Tabanidae

In field studies in Mississippi in 1973-74, the addition of internal horizontal baffles to Malaise traps had no effect on numbers of adult tabanids collected or on the species representation. The number of tabanids collected in unbaited Malaise traps with an opening that was 4 ft high and 2 ft wide was statistically equivalent to the number collected in a standard trap with a 4 X 4 ft and baited with CO2, but traps with an opening 2 ft high and 4 ft wide produced a mixed response depending on whether the top half or the bottom half of the standard opening was closed. When the top half was closed, the number of Tabanus subsimilis Bellardi collected was about the same as in a standard baited trap. When the bottom half was closed, the number was usually significantly less than in the standard unbaited trap. The data presented are for 7 species that were caught in sufficient numbers for analysis: T. abdominalis F., T. fuscicostatus Hine, T. lineola F., T. proximus Wlk., T. subsimilis, T. sulcifrons Macq. and Chrysops flavidus Wied.