Monarchs Eat in East Lansing during Trip to Mexico

Each fall, monarch butterflies (Danaus plexippus) from East Lansing fly south to the Mariposa Monarca Biosphere Reserve in Mexico. Butterflies that mature during the late summer in East Lansing and other habitat east of the Rocky Mountains migrate thousands of miles south to overwinter in the Mexican bioreserve before heading north again in the spring. They get as far north as the Great Plains before laying their eggs and dying. The Great Plains’ offspring of the East Lansing original butterflies then continue the species’ migration north, back to the northern habitat. The round trip migration is essentially a relay trip of three-to-four generations of monarchs, each generation starting from where the last generation left off.

The number of monarchs is down substantially in the last few years as a result of habitat loss, use of pesticides, use of herbicides, and other factors. The habitat of monarch caterpillars is limited to species of milkweed (Asclepias). The destruction of milkweed patches through mowing and herbicide use may be an important reason behind the reduction in adult monarch numbers.

Milkweed is easy to grow in East Lansing and is often used as an ornamental plant in gardens. It goes locally by the name of “Butterfly Weed.” Asclepias comes in many colors and attracts many pollinating butterflies, moths, bees, and the occasional hummingbird. The plant produces a toxin related to digitalis, a chemical found in foxglove. The toxin is harmless to the monarch caterpillar but is noxious to potential monarch predators. Birds and other predators avoid monarchs because they ingest this poison. Some other butterfly species have evolved to mimic the wing patterns of monarchs as a way to avoid being eaten.

While monarch caterpillars require milkweed as their nursery foodstuff, the adults will sip nectar from many flowers. By including milkweed species and a range of nectar-producing flowers in garden design, East Lansing residents can help monarchs on their migratory journey.