The alder leaf beetle, Agelastica alni L. (Coleoptera: Chrysomelidae), is one of the most defoliator pests of oak and alder trees. In the present study, the efficacies of three native strains of entomopathogenic nematodes, Heterorhabditis bacteriophora (ZET35), Steinernema feltiae (ZET31), and Steinernema websteri (AS-1), were tested against pre-pupae and adults of A. alni. Experiments were conducted by four concentrations under laboratory conditions in 2015. Four different temperature regimes were tested at concentration of 1000 infective juveniles (IJs)/ml under laboratory conditions. It was observed that pre-pupae were more sensitive than adults in all tests. Based on screening tests, S. websteri was the most effective isolate on both pre-pupae and adults of A. alni at concentration of 1000 IJs/ml with 79.17 and 71.11% mortality, respectively. It caused the highest mortality values at all temperatures, except for 30 degrees C against pre-pupae and adults. Results of the present study suggested that S. websteri and H. bacteriophora had significant potentials against A. alni.