Resistant potato plants influenced the parasitoid Edovum puttleri Grissell directly, as well as indirectly through eggs of the parasitoid’s host, the Colorado potato beetle, Leptinotarsa decemlineata (Say). In the field, E. puttleri parasitized more egg masses on plants with no glandular trichomes or with glandular trichomes bearing only enclosed droplets of exudate than on plants with two types of glandular trichomes (one with exposed droplets and the other bearing enclosed droplets). Trichomes with exposed droplets entrapped numerous parasitoids. Although rearing L. decemlineata on resistant plants influenced many of the beetle’s life-history traits, it did not affect the suitability of their eggs for development and survival of preimaginal E. puttleri. However, eggs from L. decemlineata that were reared on resistant potato plants reduced the longevity of the parasitoids and also reduced the number of hosts (eggs) killed by parasitoids.