Abstract: The larch sawfly Pristiphora erichsonii(Htg) is an impartant pest in North China larch(Larix principis rupprechtii Mayr). It has one generation a year in Ulanqab League, Inner Mongolia Autonomous Region and overwinters as prepupa in the soil or under the litter. When the canopy density of the larch stand is above 0.6, the use of aerosol at the rate of 0. 75kg/mu to control the larvae of 2—3 instars reached 70.1—83.2% mortality. The use of 25% Diflubenzuron Ⅲ at 20—30 g/mu by low volume spray in controlling 2—3 instars larvae reached 81.1—95.5% mortality. Digging the soil around the base of the tree in order to expose the overwintering prepupae reached 95.9% mortality.

Key words: Symphyta, Tenthredinidae, Nematinae, Sawfly, The larch sawfly Pristiphora erichsonii