During 1984 through 1986, eggs ofHeliothis zea(Boddie) andH. virescens(F.) were collected from field-grown tomato accessions varying in levels of glandular trichome-based resistance toManduca sexta(L.) (Lepidoptera: Sphingidae) andLeptinotarsa decemlineata(Say) (Coleoptera: Chrysomelidae). Eggs were subsequently held in the laboratory to determine levels of egg parasitism, mortality, and hatch. Parasitism of eggs byTrichogramma petiosumRiley andT. exiguum(Pinto and Platner) was greatest on theLycopersicon esculentum(Mill) cultivar susceptible toM. sextaand was lowest on all backcross lines (L. esculentum× PI 134417) × PI 134417) and the highly resistantL. hirsutum f. glabratumC. H. Muller (PI 134417). Regression analyses indicated that trichome density accounted for the greatest proportion of variance inTrichogrammaspp. parasitism of eggs. However, because the methyl ketones 2-tridecanone and 2-undecanone, which contribute to the insect resistance of PI 134417, occur in the glandular trichome tips, their effects on parasitism byTrichogrammacould not be separated from the effects of trichome density in this study. Egg density, canopy volume, and number of stem terminals per plot were unrelated to the percentage of parasitism by theTrichogrammastudied here.