Kleptopharmacophagy: Milkweed butterflies scratch and imbibe from Apocynaceae-feeding caterpillars

Milkweed butterflies (Lepidoptera: Nymphalidae: Danainae) are chemically defended and aposematic (Ackery and Vane Wright 1984). The chemical ecology of several species have been studied extensively, including the iconic and highly migratory Monarch Butterfly, Danaus plexippus (Brower and Glazier 1975; Boppré 1993). Danaine larvae feed on chemically defended plants from which they also extract phytochemical protection.