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Effects of artificial substrate on aquatic insect density were studied in Haines Branch, Lancaster County, Nebraska. Treatments consisted of small, medium,large, and mixed (mixture of small and medium) concrete substrates in modified basket samplers. Three replicates of each treatment were removed at 14 and 28 days and aquatic insects were then enumerated. Insects collected were chironomids (63%), mayflies ( 19%), caddisflies (15%), and beetles (3%). Mean mayfly densities, averaged over all substrate treatments, were higher on day 28 than on day 14, while the reverse was observed for chironomid densities. Mean densities for mayflies and chironomids were higher in medium and large than in small substrate samplers. Chironomid densities were higher in large substrate treatments versus medium and in uniform versus mixed substrate treatments. No significant treatment effects were found for the remaining taxa. It is concluded that neither substrate size nor heterogeneity are good predictors for insect densities in this stream.