Tenthredinidae comprises 215 species of 64 genera in seven subfamilies and 15 species of Dolerus have been recorded in Korea but there are no studies on the biological information of the genus and related plants. The field horsetail, Equisetum arvense L. is a vascular plant that reproduces by spores rather than seeds. Equisteum arvense develops extensive underground rhizomes which are resistant to herbicides so that, one established, it is extremely difficult and expensive to control. As results of the present study, E. arvense is recorded as a host plant of D. gessneri labiosus in South Korea for the first time. We provide diagnostic characteristics of D. gessneri labiosus with a discussion on a possibility of using D. gessneri as a biocontrol agent againt for E. arvense.