(Graeser) is an important pest of poplar in China, and glutathione -transferase (GST) is an important detoxifying enzyme in . In this paper, three full-length GST genes from were cloned and identified. These GST genes all belonged to the epsilon class (, , and ). Furthermore, the expression of these three genes in different tissues, including midguts and fat bodies, and the expression in association with different concentrations of tannic acid, including 0.001, 0.01, 0.1, 1, and 10 mg ml, were analysed in detail. The results showed that the expression levels of , , and were all the highest in the fourth instar larvae; the expression levels of and were the highest in fat bodies, while the expression level of was the highest in midguts. Furthermore, the expression of mRNA was induced by tannic acid in . These studies were helpful to clarify the interaction between plant secondary substances and herbivorous insects at a deep level and provided a theoretical foundation for controlling .