Mandible and maxillary stylet lengths in adult female thrips were measured in eight species of herbivores, six species of predators, and one species of a fungivore. Species studied live in the Mojave Desert or adjacent habitat in southern Nevada or western Arizona. Lengths of each structure were compared between Terebrantia and Tubulifera and between herbivores and predators in each suborder. Mandibles were longer in Terebrantia and in predators compared with herbivores in the suborder. Mandible length did not differ between diets in Tubulifera. Maxillary stylets were longer in Tubulifera, in herbivores compared with predators in the suborder, and in predators compared with herbivores in Terebrantia. Longer mandibles in the predatory Terebrantia may be related to greater thickness or hardness of arthropod cuticles compared with plant cuticles. Longer stylets in the herbivorous Tubulifera would enable thrips to feed on deeper plant tissues. Stylet length in predators approximated mandible length in four of the species, suggesting the stylets only exceed the arthropod cuticle to withdraw food. The mandible in the fungivorous species was longer than in other Tubulifera, and maxillary stylet length in the species was similar to herbivores in the suborder. Examination of a greater number and diversity of species of thrips may detect similar differences in mouthpart structure between herbivores and predators.