The eastern spruce budworm, Choristoneura fumiferana Clem., Lepidoptera:Tortricidae (n=30, ~500Mb), is the most widely distributed and destructive defoliator of several conifers in Canada. Extensive studies have been conducted on the identification of new target sites at a molecular level for biorational insecticides, and the development of transgenic viral insecticides. More than 30 full-length cDNA sequences of C. fumiferana have have been isolated and characterized. They are involved in several physiologically important processes such as: molting; hormone regulation, diapause; insecticide resistance; nuclear transcription factors, CHR3 and E75 (Palli et al.1996 and 1997 ); juvenile hormone esterase (Feng et al. 1999); ecdysone receptors (Perera et al. 1998; Perera et al. 1999a, 1999b); diapause-associated proteins (DAP1 and DAP2) (Palli et al. 1998; Palli et al., 2001); glutathione S-transferase (Feng et al. 1999b; 2001); phosphate transport protein (Feng et al. 1998); chitinase (Zheng et al. 2002; Zheng et al., 2003); RNA helicases (Zhang et al., 2003); ATP-binding cassette transporter gene (Hu et al. 2001; Retnakaran et al. 2001), etc. These studies have allowed us to better understand the growth and development of the insect and to develop new strategies for pest control.