ABSTRACT We compared the densities of the milfoil weevil (Euhrychiopsis lecontei) on Eurasian (Myriophyllum spicatum, exotic host) and northern watermilfoil (M. sibiricum, native host). Two lakes in Washington, Corral Lake (northern watermilfoil) and Sawyer Lake (Eurasian watermilfoil), were surveyed throughout the summer in 1998. In addition, we surveyed 17 lakes once during the summer of 1999 to determine instantaneous densities of the weevil. Summer densities (all life stages) in Corral Lake ranged from 0.2 to 0.6 weevils/stem in 1998, with the greatest numbers of weevils observed the end of June and mid August. In Lake Sawyer, summer densities ranged from 0.0 to 0.8 weevils/stem in 1998; density was highest in June and declined during the summer. The weevil appears to have at least two generations during the summer on Eurasian and northern watermilfoil. The instantaneous density of weevils (all life stages) ranged from 0.0 to 0.6 weevils/stems in 1999. Densities were greater on northern than on Eurasian watermilfoil, but these differences were not statistically significant. Weevil density, however, was positively correlated with the percentage of stems with larval damage, but negatively correlated with the length (parallel to shore) of the watermilfoil bed. No significant relationships were found between weevil density and water quality or watermilfoil frequency of occurrence. Results indicate that neither density nor the number of summer generations differ significantly between the weevil's native and exotic host.