Herbivorous Insect Populations in Oil Refinery Effluent Holding Pond Series

Oil refinery effluent holding pond populations of bottom-dwelling midge fly larvae, family Tendipedidae, were sampled monthly from November 1960 until November 1961. Population fluctuations were related to effluent toxicity. Life histories were studied for three species of tendipedids that occurred in the pond system. Estimates were made of average life-spans, survival fractions, and emergence of adults. Effects of filter-feeding larvae upon effluent turbidity were evaluated. Caloric contents of standing crops were determined, and the amount of energy lost by adult emergence was calculated. Larval midge fly populations generally increased in successive holding ponds during summer. Winter populations were small and concentrated in ponds near the center of the pond system. Larval populations of Tendipes plumosus predominated during spring. Harnischia tenuicaudata was the most abundant species in summer, and large numbers of Tanypus stellatus were presented in fall and winter. Emergence of adult tendipedids removed about 62,500 kcal/year from the system. Filter-feeding midge larvae decreased effluent turbidity significantly.