Abstract • The effectiveness of optimal spray period intervals based on mean daily temperatures were evaluated as a spray-timing tool to control high density populations of the Nantucket pine tip moth Rhyacionia frustrana (Comstock). • Initial tree growth realized from first generation R. frustrana control was compared to that from conventional applications of one insecticide treatment scheduled for each of three annual generations. • The optimal spray period intervals provided by Fettig et al. (2000a) were highly effective for controlling R. frustrana infestations. The control group averaged 47.0 ± 2.2% whole tree damage for all sites and generations as compared to 0.6 ± 0.2% for the treated group. • Volume gains attributable to R. frustrana control averaged 16.9%, 46.4% and 98.6% for first generation control, and 46.6%, 72.7% and 146.3% for conventional applications of one insecticide treatment scheduled for each of three annual R. frustrana generations at Northampton, Halifax I and Halifax II, respectively. Growth returns increased as mean damage estimates increased for both treatments, suggesting that returns realized from a single, first generation application are likely to increase with population density.