The monarch is known throughout North America for its vast migrations and communal winter roostings, as well as its poisonous properties and resulting mimicry by the vicery. The strength of its poison varies by individual, between sexes, and among populations, depending upon which milkweed has been ingested.
To send chemical messages to females, males have pronounced black spots, or scent pouches on their hind wings and elongated hairs called hair-pencils on their abdomens.
Though not abundant in the Southwest, there are pockets of breeding monarchs where milkweeds are available. More people see monarchs during their 3,000-mile fall-migration southward from Canada than at any other time of the year. The monarchs’ strong flight, which averages around ten miles per hour, enables them to evade predators relatively easily.