Influence of corn plant densities (37,000, 54,600, and 71,300 plants/ha), time of day, and plant growth stage on adult western (WCR) (Diabrotica virgifera virgiferaLeConte) and northern (NCR) (D. barheriSmith&Lawrence) corn rootworm population estimates was studied in eastern Nebraska during 1981 and 1982. Populations of both NCR and WCR adults were affected by plant density. Smaller populations of beetles were present in low plant density plantings. Adjusting beetle counts (whole-plant and ear zone) for plant density resulted in better estimates of the beetle population. Beetle counts for both species were significantly correlated with the actual beetle population. However, there were higher correlations between beetle counts and actual beetle population when counts were adjusted for plant density and expressed on an area basis. WCR beetle counts adjusted for plant density were highly and significantly correlated with number of eggs laid. With only one exception, NCR beetle counts adjusted for plant population were also highly correlated with number of eggs laid. Unadjusted counts were not significantly correlated with egg numbers.