Monarch Feeding on Nectar

Behind the Bascom House at Shaw Nature Reserve in Gray Summit, along the split rail fence that runs down toward the Glassberg pavilions, there’s a long row of butterfly milkweed growing that makes it a perfect place to watch for monarchs.

The bushy plants with small, bright orange flowers aren’t overly large or showy, but they are a haven of sorts for monarch butterflies, especially this time of year as they migrate through Missouri on their way to Mexico, where they will overwinter in the oyamel fir forests high in the mountains.

Last week, a single monarch was spotted flitting through the milkweed, drinking nectar from the flowers, but many more are on their way, says Lydia Toth, senior manager of education at Shaw Nature Reserve.

For the last 10 years or more, Toth has participated in Monarch Watch, a citizen science program based out of the University of Kansas that tracks monarch migration by catching and tagging the butterflies with small, round sticker-like tags and then releasing them to continue their southward migration.

Toth is one of several staff members at Shaw who participate in Monarch Watch in their home gardens, but she also leads school groups, from elementary age to college, that visit Shaw in September and early October on how to catch and tag monarchs.

It’s not as hard as it might sound, Toth said. The butterflies are tougher than people think, and children are shown how to be gentle with them.

Two-Way Migration

The monarchs that are passing through Missouri this time of year are the fourth (possibly the fifth) generation of those that left Mexico in the spring on their journey north, said Toth.

Those that make it to Mexico will overwinter there until around March next year, when they will head north. The monarchs that leave Mexico will stop around southern Texas, where they will lay eggs on milkweed plants.

Those eggs will hatch caterpillars that will become the second generation of monarchs who will continue the journey north, repeating the process a time or two before they reach as far north as Minnesota or even Canada.

Toth has been watching monarch eggs laid on milkweed in her home garden hatch into caterpillars who are feeding now, soon to form a chrysalis and begin the evolution to butterfly.

“As they emerge, they are going to be the ones to fly down to Mexico,” said Toth.

They will make numerous stops along the way, but not to lay any more eggs, said James Trager, naturalist at Shaw Nature Reserve and Monarch Watch participant. They will only be stopping to feed.

“In their travels, they roost overnight in trees, and first thing in the morning, they will drift down to the nearby flowers to tank up,” said Trager, noting they require a carb-rich diet because of how much energy they expend in the long migration.

The reproductive systems of this final generation headed to Mexico are not active yet, said Trager.

Those that make it to Mexico will cluster together in the cool, moist climate of the oyamel fir trees in a sort of hibernation state. As the temperature begins to heat up in late February and early March, the monarchs’ reproductive systems are triggered, and they start moving north again, Trager explained.

“It’s really an amazing phenomenon,” Toth remarked, noting the last generation can live for nine months, compared to just three to five weeks for the previous generations.

Monarch or Viceroy?

People who are new to monarch watching and tagging may get the monarch mixed up with a similar looking butterfly, the viceroy. They are both a striking orange color with black veins, but the viceroy is smaller in size and the veinage on their wings is different.

It doesn’t take long for someone to learn how to differentiate between the two, said Toth.

“On the monarch there is a dark vein around the wings, and on the viceroy there are two veins,” she said.

Let the Tagging Begin!

Monarch tagging is only done in the fall, as they are migrating south to Mexico.

People who want to participate in the Monarch Watch program need to order the tags through the website They come with specific instructions on how to do the tagging along with information on butterfly nets, tips on catching monarchs and details on how the data is used.

Each tag, which is about the size of a pencil eraser, has a unique six-symbol code number, which is how the monarch is tracked. There is a certain spot on the wing where the tag should be placed, said Toth.

With each monarch that is tagged, there is information to record on a datasheet — the tag code, the date, male or female, location (city, state and ZIP code) and whether the monarch was reared in a classroom or caught in the wild.

It is very important also that participants record their name and contact information on their datasheets.

Datasheets should be returned as soon as participants are finished tagging for the season. They can be mailed in or downloaded in spreadsheet format and submitted by email.

For more information on those details, go to

Although the tagging process may sound complicated, it’s really not, said Toth. It’s something that even young children can help with and definitely can be educational.

The school groups that visit Shaw help with Monarch Watch as part of their science class.

“It’s an all around STEM and writing lesson,” said Trager. “They build their own nets; they do calculations; they document things.”

Some classes even spend the night.

Catching the monarchs is probably the trickiest part of the process, but there are some tips that make it easier.

“You have to catch them while they’re on a plant. Very rarely will you catch them flying around,” said Toth.

“And there’s a bit of stealth involved,” said Trager, noting coming up from behind usually leads to more success.

“What works best is to swoop upward and loop so the net curls over,” said Trager.

Students are taught how to reach into their nets to get a hold of the monarchs. They lay them on something like a clipboard with their wings just right, put the sticker in place and then let them go.

The hope is that, from there, they make it to Mexico where they survive the winter and, come spring, begin their migration north.

Tag Recoveries

Because of the unique six-symbol tag code, it is possible to follow the monarchs that you tag. In the spring, Toth learned that one of the monarch she had tagged in her home garden had made it to Mexico, although she was a little sad because that meant it didn’t survive the winter.

It had been collected from the forest floor.

The Monarch Watch organization pays villagers in Mexico for every butterfly they collect with a tag. That expense is built into the cost of the tags when people buy them.

The majority of recovered tags are found in Mexico, according to the Monarch Watch information. Most of those recovered in the United States and Canada are found by people who know nothing about the program.

The data that is collected through the tagging process is “analyzed to test hypotheses concerning monarch orientation and navigation,” Chip Taylor, director of Monarch Watch, explained in his July 2017 newsletter.

“The data also are used to determine mortality during the migration and estimate the number of monarchs in the overwintering population.”

The information is later summarized and posted on the Monarch Watch website.

Migrant Here From Fir Forest

Because of the Monarch Watch tagging system, the staff at Shaw Nature Reserve were able to determine that one of the monarchs stopping here was a first generation directly from the oyamel fir forest in Mexico.

“This spring, around the end of March or early April, we were seeing monarchs a month before we normally do, showing up all worn out and beat up,” said Trager. “They were not the fresh newborn ones we normally see.”

Usually that first generation is stopped by the cooler weather still lingering in the Midwest, but a warmer than usual spring kept them flying further north right in to Missouri. Luckily there was milkweed and nectar flowers up early too, said Trager.

If You Don’t Want to Tag

The more people who participate in the Monarch Watch tag program, the better, and Toth and Trager said the staff at Shaw are happy to answer questions people may have. They don’t hold classes or programs however, because there is no way to guarantee monarchs will show up.

People who don’t want to tag monarchs but still want to contribute to the data can participate in the Journey North program, inputing information on adult monarchs, peak migration, roosting monarchs and breeding monarchs.

For more information, go to

To Get Involved

Teachers who are interested in scheduling a Monarch Watch program at Shaw can contact Toth at

If you would like to buy monarch-friendly plants or learn more about monarchs and tagging, there are a number of events throughout September to help:

Friday, Sept. 8 — Shaw Nature Reserve Wildflower Market, 4 to 7:30 p.m. at the Glassberg Family Pavilions behind the Bascom House.

Saturday, Sept. 9 — Monarch Madness at Weldon Spring Site in St. Charles, 10 a.m. to 3 p.m. Free to all.

Sept. 11, 12 and 15 —Monarch Tagging, Weldon Spring Interpretive Center, 7295 Highway 94 South, St. Charles, 9 a.m. to noon, ages 8 to adult.

Thursday, Sept. 21 — Monarch Tagging, August A. Busch Memorial Conservation Area, 9 a.m. to noon, ages 8 and up. Meet in the garden in front of the Weldon Spring Interpretive Center, 7295 Highway 94 South, St. Charles.

Friday, Sept. 22 — Mighty Migration, Powder Valley Conservation Nature Center, 9:30 a.m. to 11:30 a.m. (ages 7-12). Registration required beginning Sept. 8. Call 314-301-1500.