Since plants are sessile organisms, they have evolved various mechanisms to combat herbivores attacking them. One of these adaptations is the production of terpenes, a form of secondary metabolite. In our study, we determined the effect of guaiazulene, a terpene type, on the survival of Hyphantria cunea larvae. For this reason, the 1st generation larvae were collected from Bafra District of Samsun Province, Turkey in 2020 and were let to feed on the control diet until the pupal stage. Individuals originating from the 1st generation adults fed on the control diet in the first two larval stages and fed on the artificial diets containing different concentrations of guaiazulene in the third larval stage used in our study. As a result of our study, we found that the mortality rate of the larvae exposed to increasing concentration of guaiazulene increased. Based on the results of this study, we suggest that guaiazulene is toxic to the larvae and can be used in pest control as an alternative insecticide.