Extracts of the three lichen species; Lecanora muralis (Schreb.) Rabenh., Letharia vulpina (L.) Hue and Peltigera rufescens (Weiss) Humb. were tested against the 4th larval instar and adults of the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae). Results showed that the three extracts had insecticidal effects on larvae and adults of the pest. Treatment with the extracts of L. vulpina and P. rufescens led to highest percentages of mortality (reached 100%). The extract of L. muralis caused the least mortality rate. Mortality rates, 120 hrs post treatment with the highest extract concentration (20 mg/ml) of L. vulpina, P. rufescens and L. muralis, were estimated as 100, 100 and 76.66% for the 4th larval instar and 100, 100 and 63.33% for adults of L. decemlineata, respectively, compared to no mortality in the control.