
Scientific articles have documented on a few occasions attacks of wasps of the genus Polistes (family Vespidae) on monarch caterpillars. In fact, these wasps (adult stage) capture caterpillars mainly to bring them back to the nest where they will offer them to their larvae (Richter 2000).
In the case of monarch caterpillars, it was mentioned that Polistes prefer caterpillars less loaded with cardenolides, as these are more nutritious for their descendants (Rayor 2004). Thus, there is a potential for adaptation in monarchs, as they may lay eggs specifically on cardenolide-rich milkweeds to decrease the risk of predation on its caterpillars.