Sumielin, a smoking insecticide with fenvalerate as the effectiveingredient, was tested aganist the Massons pine caterpillar, Dendrolimuspunctatus, both in laboratory and in forest. Contact toxicity was determinedas the primary action markes. It lasted for more than 7 days when sprayedin foresty and was rainfast. The effective dosage was 1--1. 6g/mu. Contactof 5th or younger instar larvae for over 60 seconds resulted in good effic-acies. As compared to conventional ground spray of oil emulsion, the smokinginsecticide caused higher mortalities, with working efficiency increased by3--4 times, and cost decreased by 43.3%. Operative technology for applyingthe insecticide under various forest conditions is discussed in the presentpaper.