Abstract: Entomopathogenic nematodes of the species Steinernema carpocapsae,S. feltiae and H. bacteriophora were evaluated for their efficacy in killing larvae and adults ofColorado potato beetles. In laboratory assays on potato leaves, S. carpocapsae proved to be themost virulent species against the larvae. On whole plant assays in a climate chamber the efficacywas significantly enhanced by a surfactant-humectant formulation while the formulation aloneresulted in a non-significant increase in larval mortality compared to the untreated control. Adultsbeetles could not be controlled by application of nematodes to the soil but were killed after beingin contact with S. carpocapsae in a gel-formulation for as little as 30 minutes.