[Objectives]  To analyze the olfactory mechanism by which Hippodamia variegata, a common, predatory, natural enemy of aphids in the cotton fields of Xinjiang, China, identifies prey. [Methods]  Electroantennography (EAG) was used to test the electrophysiological response of 3–5-day old H. variegata adults and 2-3 instar larvae to the aphid alarm E-β-Farnesene (EBF) pheromone and the aphid sex pheromone Z, E-Nepetalactone. The chemotactic response of adults and larvae to EBF and Z, E-Nepetalactone was analyzed in a Y-tube olfactometer. [Results]  EAG results showed that both EBF and Z, E-Nepetalactone could trigger a concentration dependent EAG response in male and female adults and larvae. The results of the Y-tube olfactometer experiments showed that adult males were significantly attracted by a high concentration of EBF (100 μg/μL), and that larvae were significantly attracted by a low concentration of EBF (10 μg/μL). Both concentrations attracted adult females. Moreover, both male and female adults were significantly attracted by a high concentration of Z, E-Nepetalactone (100 μg/μL), whereas a low concentration (10 μg/μL) was only attractive to larvae. [Conclusion]  The aphid alarm pheromone EBF, and the sex pheromone Z, E-Nepetalactone elicited EAG and chemotactic responses in H. variegata adults and larvae. It is likely that H. variegata uses these pheromones to locate aphid prey. Our research provides a theoretical basis for the development of integrated pest management strategies, such as attractants for aphid predators.