Monarchs and Milkweeds

Nature Notes from Kankakee Sands

This month's Nature Notes was written by Alyssa Nyberg. Alyssa has been managing the Kankakee Sands Native Plant Nursery for the past 15 years.

At Kankakee Sands, we have 68 different species of butterflies, and my daughter Savanna and I are excited to see every one of them! She and I enjoy walking the restored prairies of Kankakee Sands and trying to spot as many butterflies as we can. We often see the regal fritillary butterfly, spicebush swallowtail, tiger swallowtail, great spangled fritillary, morning cloak, and buckeye. But it’s the monarch that we are looking forward to seeing the most this year.

As I write, the monarch is making its way from Mexico; it should be migrating back to our area later this month. Leading up to their arrival, Savanna and I planted milkweed seedlings in the Kankakee Sands greenhouse, her little fingers placing the milkweed seedlings tenderly into the pot and covering them with soil.

Why milkweed? Well, the adult female monarch butterfly lays her eggs on milkweed plants, typically on the underside of a leaf. It is estimated that a female monarch can lay 100 to 300 eggs in her short lifetime! After just four days, the egg hatches. A caterpillar emerges and begins feeding on milkweed leaves, its sole source of food. Without milkweeds, there would be no monarchs.

At Kankakee Sands, we have nine species of milkweeds for monarchs to dine upon: Butterfly weed (Asclepias tuberosa), Swamp milkweed (Asclepias incarnata), Whorled milkweed (Asclepias verticillata), Sand milkweed (Asclepias amplexicaulis), Sullivan’s milkweed (Asclepias sullivantii), Tall green milkweed (Asclepias hirtella), Short green milkweed (Asclepias viridula), Purple milkweed (Asclepias purpurescens), and Common milkweed (Asclepias syriaca).

Milkweed plants contain cardiac glycocides and have a bitter flavor. Monarch caterpillars build up these toxic steroids in their tissues. When a bird or other predator preys on a monarch caterpillar or butterfly, it associates the bad taste with the color patterns of the caterpillar or butterfly and avoids preying on them in the future.

As the caterpillar eats, it grows, and as it grows, it will molt. Caterpillars actually eat this shedding. Caterpillars shed five times while they are in the caterpillar stage. After feeding on milkweeds for nine to fourteen days, the caterpillar will find a leaf or twig to hang from, and it will create a chrysalis. While inside a chrysalis, its body tissues and organs are broken down and re-arranged over the course of nine to fourteen days to create the adult butterfly. (To me, this is the magical part.) At long last, the newly formed butterfly will begin to hatch out of the chrysalis, eventually spreading its wings for the very first time and taking flight.

The lifespan of each particular monarch butterfly depends on when they emerge as a caterpillar and whether or not it will migrate. Those monarchs that are born in the early summer will have the shortest life – about two to five weeks. Monarchs that emerge in the late summer and migrate south will live much longer, approximately eight to nine months.

Many of the late summer monarchs will travel the longest migration route of any butterfly in the world. In Autumn, monarch butterflies travel around 3,000 miles to inhabit the mountains of central Mexico or small groves of trees along California’s coast. Monarchs are cold-blooded insects that cannot survive the long, cold winters of temperate climates. Their migration is a natural survival instinct.

As they fly south, monarchs may fly as high as 4,000 feet, averaging twelve miles per hour.

Butterflies west of the Rocky Mountains will migrate to the California coast. Monarchs east of the Rockies will migrate to the Transverse Neovolcanic Belt in central Mexico. Both sites have large stands of trees where the monarchs can cluster together, and surrounding habitat with underbrush, streams, fog and water, all necessary for providing moisture and protecting the butterflies from wind and snow. 

The monarchs that we see at Kankakee Sands overwinter in central Mexico. Historically, tens of millions of butterflies overwintered in less than twenty sites in Mexico, gathering in roosts of 20-30 million. In late February and early March, the monarchs mate in Mexico and then begin flying north. They typically arrive in Texas before laying their eggs on milkweed plants. The next generation continues the migration from Texas, leapfrogging north until the third or fourth generation arrives as far north as Canada in May and June.

Many organizations and researchers are concerned about the declining number of monarch butterflies. The decline is likely linked to the overwintering habitats in Mexico being targeted for new roads, housing developments and agriculture expansion, as well as a lack of milkweeds and habitat along their migration routes on which to feed and lay eggs.

There is action you can take to ensure the monarch’s survival. You can create habitat for the monarch in your backyard, school, or office by planting milkweeds and native plants, even potted outdoor plants can make a difference. Encourage your friends, neighbors and relatives to do the same. Additionally, be sure that the landscaping plants you are purchasing are not treated with neonicotinoids, a chemical widely used in the ornamental industry to kill greenhouse pests, but which also kill all insect pollinators, including butterflies and bees.

This summer at Kankakee Sands we will be creating a Monarch Trail for the public and the butterflies to enjoy, using some of the very milkweed plants that Savanna and I transplanted this year. (Stay tuned for more information about the trail opening.) With luck, Savanna may have the joy of a monarch landing on her fingers, the very same fingers that planted the milkweed seedlings.

 

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