The monarch butterfly is known for its bright orange and black wings, which signal to potential predators that the species is poisonous.
Adult monarch butterflies have wingspan of about four inches. Their bright orange upperwings are interlaced with black veins and surrounded by a wide, black border marked with white spots. The undersurface of their wings are colored a duller orange to camouflage the species against tree bark. Males are slightly larger than females, and they have a black spot on each hind wing. Monarch caterpillars have black, white and yellow bands over body with a pair of long black filaments near head and a pair of shorter filaments near rear.
The monarch's range of breeding habitat depends on presence of milkweeds, the single "host plant" and food source for monarch caterpillars. Adults are often found in fields, meadows, marshes and roadsides where these plants are common. Adults make annual long-distance migrations to overwinter in fir, pine, oak and cedar forests.
The monarch butterfly's expansive range extends through much of North, Central and South America. In North America, two distinct populations exist: one that breeds in the east, and one that breeds in the west. Introductions during nineteenth century have led to species becoming established in Australia, Indonesia and several Pacific Islands, as well as the Canary Islands and Spain.
Monarch caterpillars feed on milkweed plants, while adults forage for flower nectar.
The bright coloring of adults warns potential predators the species is poisonous, thanks to the accumulation in their bodies of toxic chemicals produced by milkweed plants. However, caterpillars are preyed upon by some invertebrates, like wasps and ants.
Monarch mating occurs throughout summer and once again in spring before adult butterflies migrate from their overwintering sites. During courtship, the male pursues and nudges the female in the air before taking her down to the ground to mate. Females lay small eggs on milkweed "host plants," often on the underside of leaves. Once hatched, caterpillar eats almost constantly over a nine-day to two-week period, shedding its skin several times before forming a chrysalis around itself and transforming from into a butterfly. The lime-green chrysalis is marked with gold spots and a black, horizontal band edged with gold.