Last time I discussed milkweed plants, more specifically the western whorled milkweed. This week I thought I would cover two beasties in the garden that use milkweed plants as hosts, both flowers as adults and leaves as caterpillars. These are the monarch and queen butterflies.
The milkweed family of butterflies has worldwide distribution represented by many different species. Most are found in the tropics but others can be found in India and Africa. They are quite diverse in their appearance representing several genera and species. What they all have in common is that their caterpillars feed on one or more of the roughly 300 kinds of milkweed and in so doing ingest a mild plant poison that makes them unpalatable to their predators. Queen caterpillars also feed on dogbane, another mildly poisonous plant.
Our two milkweed butterfly species are the monarch, Danaus plexippus, and the queen, Danaus gilippus. The viceroy butterfly, Limenitis archippus, is not a milkweed butterfly at all but looks very close in appearance to the monarch. It belongs to the admiral butterfly group. It may occur here but I haven't seen one. Viceroy butterfly caterpillars feed on leaves of willow, poplar and cottonwood trees. They ingest salicylic acid from their leaf diet and hence are also unpalatable to predators as adults and caterpillars. The monarch and the viceroy are mimics of each other and by resembling each other they reinforce their distastefulness to their shared predators.
Both the western population of monarchs and queens are summer residents of Colorado. Our monarch invades our state each year as it migrates northward. And each fall it returns to its overwintering sites in southern California and Mexico. It is the eastern population of monarchs that participate in the well-known long-range migrations to Mexico for the overwintering.
The queen butterfly is smaller than the monarch, 2.5-3.5 inches versus 3.5-4.0 inches, and easily separated from the monarch by its more uniform browner coloring and less veining -- see comparison pictures. Both monarch and queen butterfly males have black scent patches on the upper surface of their hindwings. Queens are much less common than monarchs in our area.
The caterpillars of monarchs and queens are similar in appearance, with vibrant stripes of yellow, white and black. Queen caterpillars are darker than monarchs. Both species of caterpillars have two pairs of long, fleshy tubercles or filaments, one pair at each end.
Adult butterflies can be attracted to your garden by planting milkweed, coneflowers, coreopsis, asters, marigolds, zinnias and cosmos. They also seek out dogbane, goldenrod and thistle flowers.
While much to-do has been made about the drastic reduction in numbers of monarchs in our country, most of this has been with the eastern population due to poor winter conditions and deforestation of their Mexican overwintering sites. In the Surface Creek and North Fork areas, milkweed plants are abundant and readily available as host plants for our two prized royal butterflies, the monarchs and queens.
Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.