Ipomopsis aggregatais the 2nd host plant found for larvae ofHylemyasp. Although the behavior of ovipositing females onI. aggregatais quite similar to their behavior onPolimonium foliosissimum, evidence is presented indicating that an oviposition-deterring pheromone is not being deposited onI. aggregataflowers. These females are, however, able to recognize and respond to the ovipositon-deterring pheromone deposited onP. foliosissimum. Although manyHylemyaeggs are laid on singleI. aggregataflowers ample larval resources are insured for eachHylemyalarva by a very high level of egg mortality.