Our group at Cornell has been evaluating hemp (Cannabis sativa <0.3% THC) cultivars since 2017, including cultivars bred for grain, fiber, and cannabinoid markets. Small plot field trials in 2019 included cultivars bred in Ukraine that were known to be cannabinoid free (chemotype V) and these four in particular were significantly damaged by foliar feeding insects, primarily Japanese beetle (Popillia japonica). In order to test the relationship between cannabinoid content and insect herbivory, we obtained an F2 population developed by John McKay’s lab by crossing ‘Carmagnola’ × ‘USO-31’. We grew out 280 seedlings from this population with 140 on each of two field sites in Ithaca and Geneva, NY. We collected leaf tissue for cannabinoid analysis and assessed foliar herbivory weekly, which was compiled into area under the herbivory progress curves (AUHPC). The plants were also genotyped using PACE markers that reported the alleles at the B locus which distinguish chemotype III and IV plants and also a PACE marker designed to detect a SNP in the O locus, which detected chemotype V plants. The F2 population fit a Mendelian segregation ratio of 9:4:3 chemotype III:V:IV with quantitative variation in CBD and CBG content in the chemotype III and IV plants respectively. AUHPC was significantly greater for chemotype V plants compared with chemotype III and IV and was inversely proportional to total cannabinoid content. Selected chemotype III and V plants (6 genotypes of each) were propagated and leaves were used for no-choice feeding assays with cabbage looper (Trichoplusia ni). The T. ni larvae performed better on cannabinoid-free leaves than on CBD-dominant leaves. We also conducted feeding assays with artificial diets with two methods for adding cannabinoids – incorporating CBDA or CBGA into the diet at two concentrations or painting increasing concentrations of CBDA or CBGA on the surface of the diet. With both bioassays, increasing doses of CBDA or CBGA impaired cabbage looper performance and led to mortality at higher doses. These results strongly suggest a role for cannabinoids in defense against at least some foliar feeding insects in hemp.