Keith Anderson didn’t intend to raise monarch butterflies. However, when he planted their main source of food in his rain garden, they came to him.

His newly transplanted milkweed didn’t stand a chance.

“(Monarchs) ate it down to a nub,” he said.

Milkweed is the sole source of food for monarch caterpillars. Decline of the plants has correlated with a decline of monarch butterfly populations. The eastern population of monarchs has dropped by more than 80 percent and an estimated 3 percent of the western population remains, according to a National Geographic report.

That same report explains how planting milkweed in cities and towns could help monarch populations rebound. Anderson has notably done that and has taken his commitment beyond that. When Anderson read that monarchs have about a 2 percent chance of surviving from egg to butterfly, he decided to do what he can to up those odds.

Monarch Butterflies

Keith Anderson searches for monarch butterfly eggs Thursday, June 6, 2019, outside his home in Rochester.


Beginning in late May each year, Anderson combs through his gardens for monarch eggs. Light green and the size of a pen tip, it helps to know what you’re looking for and where to find them.

Most are laid on the underside of milkweed plant leaves. He collects the leaves that have eggs and places each on a damp paper towel in a plastic container with holes in the lid. He covers the holes with fabric to keep caterpillars from escaping. The moist towel keeps the leaves relatively fresh since they’re an important source of food for the hatchling caterpillar.

Monarch Butterflies

Keith Anderson uses a magnifying glass to get a closer look at a monarch butterfly egg Friday, May 31, 2019, at his home in Rochester.

Eggs usually hatch in about four days after being laid. A small black dot appears in the egg when the caterpillar is ready to emerge, Anderson said.

“That’s its head,” Anderson said.


When the caterpillars hatch, they eat their egg and then alternate between eating the milkweed leaf and sleeping. At about four to five days old, Anderson moves the caterpillars into mesh laundry hampers.

“These are from Ikea, but you don’t need to go that fancy,” he said.

By then, the caterpillars are big enough they don’t escape through the holes in the mesh.

Monarch Butterflies

A monarch butterfly caterpillar at the home of Keith Anderson Thursday, June 20, 2019, at his home in Rochester.

He puts stalks of milkweed from his garden with them. Anderson uses floral tubes to keep the milkweed fresh.

At about day ten after hatching, the caterpillars’ growth and appetite go into high gear.

“When these 25 get to day 10 or 11, those stalks I put in there now wouldn’t last a day,” he said.

This is where Anderson keeps the caterpillars until they’re ready to go into chrysalis. From hatching to chrysalis takes about 16 days. In that time, they gain about 4,000 percent of their initial body weight. To fuel that, it takes milkweed from his garden — a lot of milkweed. He cuts his milkweed stalks just above the lowest pair of leaves on the plant. Two stalks will sprout from the plant at that point if you leave at least a pair of leaves.

“It’s kind of a renewable resource,” he said.

As caterpillars get ready to go into chrysalis, they stop eating and climb as high as they can. For Anderson, that means the hamper lid. They then spin silk, attach itself to the silk and hang upside down. They then curl their bodies slightly, making a “j” shape. They then shed their skin.


After 10 days, the butterflies emerge. Anderson watches the process happen in the morning and in the afternoon, he releases them.

The butterflies emerge with soft, small wings. Over about a half hour, they push fluid into the wings to inflate them. After about three hours, the wings harden enough for the butterflies to be able to fly.

The first generation Anderson raised this year emerged during stormy weather. Despite his coaxing, the newly emerged butterflies were reluctant to take off. Most remained in the hamper when he removed the lid.

A couple that did leave the safety of the hamper stayed nearby in the yard. Anderson collected them back into the hamper.

“They just didn’t want to go,” he said.

He prefers they put some distance between them and their temporary home when he releases them.

“I’d rather they not be eaten where I can see them,” Anderson said.

A couple days later, Anderson released another three dozen under sunny skies. Over three days, he released more than 100 butterflies.

“I figured I gave them the best chance I could,” Anderson said. “They get to go be butterflies now.”

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