The Effects Of Seasonal Changes And Irrigation Diversion On The Benthic Insect Populations Of Confederate Creek, Broadwater County, Montana

Abstract

Benthic insect populations of Confederate Creek, Broadwater County, Montana, were studied during June-August, 1979. Samples were taken above and below an irrigation diversion once a month and assayed for insect number and diversity. Five orders were represented: Coleoptera, Diptera, Ephemeroptera, Plecoptera, and Trichoptera. Numbers of insects in all orders tended to increase with each sampling. The order with the greatest population density below the irrigation diversion was Diptera. The order with the greatest population density above the irrigation diversion was Ephemeroptera. One sample was taken August 19 in the altered water route used for irrigation. One insect was found in this sample, compared to 641 insects in the sample below the irrigation diversion and 152 insects in the sample above the irrigation diversion taken the same day.