Abstract: In order to discuss the mechanism and effect of induced resistance on the growth and development of woody plants, the authors used a biological method to measure the effect of Populus deltoides on Clostera anachoreta at Beijing Forestry University, which had been fumigated for 24 h by methyl salicylic acid, in 2003.The results show that methyl salicylic acid can induce systematic resistance in Populus deltoides. The Clostera anachoreta fed on leaves treated by methyl salicylic acid reveal that the weight has declined and the nutrient metabolism is obviously impaired. This study indicates that inhibiting nutrient metabolism is a mechanism of induced resistance which retards the growth and development of insects.