Research has shown that different elm hybrids exhibit various levels of resistance to numerous insect pests. This study measured the total phenolic content of 12 species/varieties of elm tree foliage and analyzed the relationship to Japanese beetle feeding preference studies and gypsy moth developmental studies. The 12 elm species, all of Asian origin, were grown at the Morton Arboretum, Lisle, Illinois and transferred to the Pesticide Toxicology Laboratory at Iowa State University, Ames, Iowa for chemical analysis. Feeding preference and developmental suitability was determined previously in assays involving the identical trees. Significant differences in the total phenolic content of the 12 elm species/varieties were determined through ANOVA and multiple comparisons on SAS. This study is part of an on-going project to study the effect of elm foliar chemistry on insect herbivores. Results presented will include relationships between feeding preference and developmental suitability to total phenolic content as well as the most recent findings.