This neat looking fellow is the larval stage (caterpillar) of the Monarch butterfly (Danaus plexippus) feeding on Asclepias curassavica or Butterfly weed (milkweed).

Larvae of the Danaus plexippus can defoliate a milkweed plant in one to two days. Most milkweeds contain cardiac glycosides which are stored in the bodies of both the caterpillar and adult butterfly. These poisons are distasteful and emetic to birds and other vertebrate predators. After tasting a Monarch, a predator might associate the bright warning colors of the adult or caterpillar with an unpleasant meal, and avoid Monarchs in the future.

Life Cycle

Monarchs can be found in open areas in all regions of Florida year-round. Florida's Monarchs are unique in that they do not migrate out of the state during the winter (although they are thought to move further south when cold spells approach). In fact, Florida Monarchs are the most active and most visible here during the winter months. It is also thought that Monarchs from the Northeastern U.S. over-winter in Florida. It is presumed that these butterflies do not return to the north in spring, but their children do.

Monarch eggs are deposited on the underside of milkweed leaves and hatch, depending on temperature, in three to twelve days. The larvae feed on the plant leaves for about two weeks and develop into fat, colorful caterpillars about 2" long. Attaching themselves head down to a convenient twig, they shed their outer skin and begin the transformation into a pupa (or chrysalis), a process which is completed in a matter of hours.

The pupa resembles a waxy, jade vase. Packed tightly inside, the caterpillar completes the process of rebirth into a beautiful adult butterfly in about two weeks. Emerging at last from the transparent case, the monarch waits until its wings stiffen and dry and then flies away to continue the propagation of the species.

Control

Milkweeds, which Monarch larvae feed on exclusively, are considered noxious weeds by some people, as such they are often destroyed. Both milkweed and adult nectaring plants are vulnerable to herbicides used by landscapers, farmers, gardeners, and others. Monarchs and their larvae can be easily killed by many pesticides and BT (a natural caterpillar control). While there is currently no danger of the Florida Monarch becoming extinct, the loss of North American Monarch habitats in Mexico due to deforestation may contribute to the endangerment of that migratory species in other parts of the U.S. and Canada. Considering that in 15 to 20 years Monarchs in other parts of the United States may become endangered due to habitat losses, control of Danaus plexippus -- the Monarch butterfly -- in Florida is not recommended nor suggested.

Sources: Florida Butterflies; Butterfly Gardening: creating summer magic in your garden