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Every week there are new marvels to look for in the outdoors, and Discover Nature highlights these attractions. The Missouri Department of Conservation’s Josh Hartwig brings us the stories of river otters, luna moths, red buds, and other actors as they take center stage in nature’s theater.You can hear Discover Nature, Mondays at 7:42 a.m. and 5:18 p.m.

Discover Nature: Missouri's Caterpillars and Monarch Butterflies

Missouri Department of Conservation
A monarch butterfly caterpillar feeds on a milkweed plant.

Discover nature this week with Missouri's caterpillars. The bright wings of butterflies catch your eyes, and many people notice. But few notice naturally drab caterpillars.

Butterflies find mates, reproduce, and die. Caterpillars have much bigger jobs. They hatch from tiny eggs to grow into fat, fleshy larvae. Then they transform into graceful adults. All that takes lots of energy, so caterpillars are basically eating machines.

Most caterpillars only eat the leaves of certain plants. Monarch caterpillars eat milkweeds, and monarch butterflies check each plant to make sure it is a milkweed before laying eggs on it. This ensures that their young have the right food available upon hatching. Regal fritillary caterpillars eat violet leaves, and regal fritillary butterflies lay their eggs in areas where violets are likely to grow and trust that their young will inch their way to violet plants.

Monarch larvae feed on a variety of milkweeds, which contain cardiac glycosides. These chemicals are stored in the insect’s body and render it unpalatable and toxic to many predators. The bright color patterns of both monarch larvae and adults advertise their toxicity to would-be predators. As adults, monarchs consume the nectar of a wide variety of flowers, particularly New England aster and other members of the sunflower family.

Broods are produced in Missouri in summer and fall. Adults migrate to Mexico in late summer and fall; then, when they fly north in spring, they reproduce in Oklahoma or Texas. Their offspring continue northward, returning “home” some generations later. Eggs are laid in the spring and summer and hatch in about four days. After about two weeks, the caterpillar enters the chrysalis stage. The mature butterfly emerges in about two weeks.

More information about caterpillars and butterflies in Missouri can be found online at MissouriConservation.org.

Josh Hartwig is the host of Discover Nature and a media specialist for the Missouri Department of Conservation.
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