Common Name: Monarch butterfly
Scientific Name: Danaus plexippus (Linnaeus)
Description: Adult butterflies are orange with black wing veins and bodies. Caterpillars are 2-3/4 inches long fully grown, with a pair of black antennae-like appendages (filaments) at either end of the body (2nd thoracic segment, 8th abdominal segment). The body is ringed with black, yellow and white stripes. The chrysalis is smooth and light green or blue with gold markings.
The viceroy butterfly, Basilarchia archippus (Cramer) (Nymphalidae), although not closely related to the monarch butterfly, appears strikingly similar in color and pattern. It can be distinguished by the dark band arching across the center of the hind wing. This species mimics the monarchs appearance to avoid heavy predation by birds who mistake this tasty mimic for the distasteful monarch. Caterpillars feed on willow leaves and mimic bird droppings in appearance. The queen
monarch, Danaus gilippus (Cramer), is closely related to the monarch, but differs in color patterns. Butterflies lack dark-colored wing veins and the white spots on the wings are more diffuse. Larvae also feed on milkweeds, but bear an extra pair of filaments in the middle of the body (2nd abdominal segment) and each body segments bears a pair of yellow dots.
Life Cycle: Development progresses from a egg which hatches in 7 to 9 days, through five caterpillar stages (instars) in roughly 5 weeks, a chrysalis (pupa) for about 9 days before the adult butterfly emerges. Monarch butterflies (adults) migrate south through Texas from Canada and the eastern half of North America every fall to the 10,000 ft. tall hills near Angangueo, Mexico where they spend the winter (this site was discovered in 1976!). In the spring, surviving adult butterflies begin migrating north, breeding and developing through 2 to 4 or more generations as they spread north. About 100 million members of the last generation produced in the fall migrate to Mexico and live for about 9 months.
Habitat and Food Source(s): Caterpillars have chewing mouthparts. Adults have siphoning mouths. Caterpillars feed exclusively on milkweed. Adults feed on nectar from numerous wild flowers. The monarch butterflies are distasteful to birds because of chemicals obtained from caterpillar feeding on milkweed leaves.
Pest Status: Caterpillars feed on milkweed; medically harmless.
See also Butterfly Gardening in Texas.
Literature: Howe 1975; Neck 1996; Wright 1993.