In a preliminary screening for naturally occurring pesticides, bark extracts from eight tree species commonly used in the Eastern North American forest milling industry were tested for their insecticidal activities against Choristoneura rosaceana (Harr.), Conotrachelus nenuphar (Hbst.) and Sitophilus granarius (L.). Insects were treated directly with a 2 % solution using a Potter spray tower and were given food treated with the same solution afterwards. Mortality was assessed 1 and 7 days after treatment. Only the hexane extract of balsam fir bark, Abies balsamea, demonstrated a significant insecticidal activity against C. rosaceana neonates larvae. From this extract, bioactive compounds were isolated using bioassay-guided fractionation.