Competition: Butterflies eliminate milkweed bugs from a Caribbean Island.

By eliminating the food plant, Asclepias curassavica, monarch butterflies, Danaus plexippus, have virtually eliminated milkweed bugs, Oncopeltus spp., from the island of Barbados. The relatively open terrain of Barbados means the plants have no refuge; the butterflies survive on an alternate milkweed food plant, Calotropis procera, whose thick-walled pods make seeds unavailable to the bugs.