Subfamily Danaiinae: Milkweed Butterflies All milkweed butterflies lack scales on their antennae. Most are fairly large, with orange and black markings, or else black with blue and green iridescence. By feeding on members of the plant family Asclepiadaceae, milkweed butterflies acquire distasteful chemicals that confer protection from predators, especially birds; and many species are involved in mimicry complexes. They also visit plants containing chemicals that serve as precursors for making the pheromones necessary for sexual identification and attraction. Males store the pheromones in velvety pads of androconial scales on the hindwings called alar pouches; they also possess eversible brushes in the abdomen, so called hair pencils, which they rip on the sex brands, then open, to waft their perfume near the antennae of the females, rendering them receptive.