Dietary conjugated linoleic acid (CLA) has been shown to have biological effects on mammals including exhibiting anticarcinogenic and antiatherogenic effects, influencing lipid metabolism and protein deposition, and enhancing immune function. CLA-enriched diets have been shown to alter the fatty acid composition of hen egg yolk lipids. A CLA-enriched diet has been shown to adversely affect the rate of egg production and body weight gain of hens. Our hypothesis is that insects may be affected by dietary CLA similarly to hens; they may exhibit decreased egg production, altered fatty acid profiles of the eggs, and growth inhibition. Our objectives in this study were to examine the effects of CLA on the survival, development, and egg production of the European corn borer (ECB), Ostrinia nubilalis. ECBs were fed artificial diet optimized for ECB with various amounts of CLA or safflower oil (0.005 to 5.0% of the diet) and reared to maturity in individual diet cups in an incubator set at 80 o F with 70-75% humidity and constant lighting. Pupal mass was measured, and maturation rate was monitored by measuring time to pupation and adult emergence. After emergence, adults will be kept for breeding trials to study effects on egg production and fatty acid composition of the eggs. Males from the CLA-treatment groups will be bred with both CLA-treated and untreated females; untreated males will also be bred with both CLA-treated and untreated females. Egg masses will be collected and the fatty acid profiles determined.