Phytoecdysteroids are plant-derived ecdysteroids. Phytoecdysteroids are a class of chemicals that plants synthesize for defense against phytophagous (plant eating) insects. These compounds are mimics of hormones used by arthropods in the molting process known as ecdysis. Ecdysteroids identified in plants are named phytoecdysteroids, and those from animals are sometimes called zooecdysteroids.