Cydia toreuta population densities, prolonged diapause behavior, parasitism and adult emergence patterns were examined over four years at two red pine locations in Wisconsin. Last-instar densities ranged from 0.54 to 3.18 per cone. This was considered a wide range for this species in red pine. Population clumping was evident at last-instar densities below 2.90, however no consistent pattern was evident between years. Clumping disappeared at populations greater than 2.90 last-instars. Prolonged diapause varied from 7.8 to 38.9070. Parasitism rates var ied from 10.9 to 46.6 %. Phanerotoma toreuta (Hymenoptera: Braconidae) was the most abundant parasite at both sites and emerged in unison with male C. toreuta. Estimation of percent of last-instars undergoing prolonged diapause prior to spring emergence can be accomplished using forced emergence though cones should be collected after 31 January. Estimation of percent parasitism can be made as early as November. Resident moth populations could be estimated prior to spring flight utilizing this information. Emergence occurred over an approximately 2 week period between mid-May and early June. The majority of male moths emerged prior to females.
Katovich, S. A. and Kulman, H. M.
"Eastern Pine Seedworm, Cydia Toreuta (Lepidoptera: Tortricidae) in Red Pine Cones in Wisconsin,"
The Great Lakes Entomologist, vol 24
Available at: https://scholar.valpo.edu/tgle/vol24/iss3/3