BIOLOGY AND DISTRIBUTION OF STAPHYLINID BEETLES ASSOCIATED WITH BOVINE FECES IN SOUTH CENTRAL TEXAS

The staphylinid fauna of a south central Texas pasture was identified. Species composition were compared in two habitats; open and wooded pasture. Over 27,000 specimens of Staphylinidae were captured during a field study from March 1979 to December 1980. Beetles were collected from bovine droppings and by automated pitfall traps baited with swine feces. A total of 20 species representing at least 9 genera were identified, differences in seasonal and diel flight activity were apparent. The peak densities and the arrival time of 5 species at the dung-pat, Philonthus brunneus (Gravenhorst), Philonthus cruentatus Gmelin, Philonthus flavolimbatus Erichson, Philonthus hepaticus Erichson, and Aleochara bipustulata L. indicate these may be important predators of immature stages of the horn fly, Haematobia irritans irritans (L.) as well as other dung-breeding Diptera.;The biology of four species, P. brunneus, P. cruentatus, P. flavolimbatus, and P. hepaticus was studied in the laboratory. These species mated either on the manure or in debris immediately adjacent to the dung-pat. Eggs were usually deposited singly at the soil-fecal interface adhering horizontally or vertically to the soil or feces. Eggs are creamy, pale yellow to creamy white in coloration and oval in shape at the time of oviposition. They ranged in size from 0.8-1.0 mm in length and 0.5-0.6 mm in width for P. brunneus, 1.3-1.4 mm in length and 0.6-0.9 mm in width for P. cruentatus, 0.8-1.1 mm in length and 0.5-0.6 mm in width for P. flavolimbatus and 0.9-1.1 mm in length and 0.4-0.6 mm in width for P. hepaticus. The embryonic incubation period ranged from 36 to 53 h at 27-30(DEGREES)C; larval development consisting of 3 instars required 5-6 days. Staphylinid larvae fed readily on larvae of the house fly, horn fly and stable fly. Prepupal larvae of each of the 4 species constructed pupal cells in the soil beneath the dung pat ranging from 2-15 mm deep for P. brunneus, 12-65 mm deep for P. cruentatus, 9-32 mm deep for P. flavolimbatus and 0-1 mm deep for P. hepaticus. In each case, the pupal cell was formed by a continuous "hollowing out" motion of the prepupal larva in the soil. The pupal stage lasted approximately 5-7 days.