Abstract: Mean life tables for two generations of Lepidosaphes salicina Bersch., a main pest of shelter-forests in North China, are compiled by statiscal method. The unhatching rate of these two generations at egg stage is 66.5 and 36.0％, and their mortality at fixed nymph stage is 28.0 and 32.7％ respectively. The predation rate of 2nd instat nymph by Hemisarcoptes malus, an important natural control agent, is 36.3 and 41.6％, and the parasition rate of female adult by Aphytis procliaus is 2.2 and 7.2％ respectively. The population fluctuation trend index(Ⅰ) for these two generations is respectively 1.12 and 1.26.

Key words: Life table, Lepidosaphes salicina, Hemisarcoptes malus, Aphytis procliaus, heavy metals, strong reductive, speciation transformation, protected vegetable soil