Many plant-eating insects have developed the ability to eat plants that synthesize toxins, which they use to defend themselves against herbivores. While these specialized insects are good at dealing with specific plant toxins, plant species with highly variable chemistry can present a challenge. In a new study published in AoB PLANTS, Keefover-Ring tested for reciprocal effects of a specialist tortoise beetle (Physonota unipunctata) feeding on a host plant (Monarda fistulosa) with individuals containing two different essential oil toxins (thymol and carvacrol). Overall, beetles showed higher survival, growth, and preference for one of the plant’s essential oil types. Such intraspecific variation in plant resistance may lead to herbivore specialization on distinct host chemistry, which has implications for the evolutionary trajectory of both the insect and plant species.