Release of newly-eclosed butterflies has rich opportunities for teaching. In another post, I described the mechanics of release. This post is about what to teach.
If your time for release is very limited, here are tips how you can easily improve the experience:
- Provide a map showing where the butterflies are going, and in what direction.
- Challenge the students to identify the sex of each monarch.
- Describe behaviors the monarchs will show when released. Record the behaviors seen on a simple data sheet.
- Acknowledge your Spanish-speaking students--that we're now passing the torch of protection to our Mexican friends.
- Allow students to feed the monarchs honey-water before release.
- Create a little bit of ceremony. "Adios!"
Now here's the longer version for teachers with more time or older students. Along with viewing eclosure, butterfly release is one of the high points of the whole monarch experience. Don't fail to take full advantage of it!!
Encourage students to...
- Handle butterflies
- Empathize with butterflies
- Understand the geography
- Acknowledge cultural aspects
- Learn the basics of migration
- Do basic science by recording observations
Teachers may avoid these teaching opportunities because they don't know monarch biology. However, by asking your students questions, you can raise important issues without having to know a lot. If you ask them some of these questions, allow a bit of discussion, then give the brief answers I provide, you can look like an expert!
Up close
Handling butterflies is an opportunity to learn that some insects are gentle and friendly--a core concept underlying our program.
Monarchs are fragile upon emergence, but their exoskeletons quickly harden. Students can handle them gently by the wings four hours after they eclose (or even sooner if very careful).
It's a common misconception that you shouldn't handle butterflies because they will lose scales from their wings, possibly causing death. Yes, they will lose a few scales, but it's harmless. One function of scales is that they are easily shed, making the butterfly a little slippery--a predator defense.
Handling butterflies teaches gentleness, precision, and fine motor control. Think surgeon...
I determine sex by first looking for the spot. If I don't see it clearly, then I look for the darker, richer color of females, along with the wider black wing veins. If in doubt, hold the butterfly up to the light or against a white background, facing sideways. Pinch the wings so that the abdomen is forced down so you can see it. Look for the easy-to-see slit (photo) in the downside of the abdomen not far from the tip.
Empathy and imagination
What do you think the butterflies will do when you release them? Fly? Which way? Straight up? Land somewhere nearby? How do they know what to do?
What would you do if you woke up from a long sleep and found a gentle giant taking you outdoors? You've never been outdoors. And it tosses you into the air? What would you do? Have you ever had an experience where you did something without even thinking about it? What happens if your hand touches the hot stove? What other ways do you act without thinking? Think... a slip on the ice.
- Where are we located?
- Where are they flying to? (Just a bit west of Mexico City).
- Which direction is that from here? Southwest.
- Can the student point to the south? West? Southwest? The sun is in the south at noon; in the southwest during mid-afternoon.
- How far is that? (Roughly three thousand miles.)
- Notice how North America is like a giant funnel. They don't fly over the Gulf of Mexico, so as they head SW, the land funnels them towards the mountains of central Mexico. The mountains provide additional cues.
Most monarchs overwinter in the Mexican state of Michoacan (where our avocados come from), though a few monarch clusters are found nearby in the Federal District of Mexico, an area surrounding the capital.
Cultural considerations
Monarchs are a species we share with Mexico. Both countries will have to cooperate if we are to save monarchs. Monarchs are a great opportunity to draw both countries closer together. Monarchs arrive at their wintering grounds about when Mexicans celebrate the Day of the Dead (Nov. 2).
Most classes will have students who speak Spanish and may have relatives in Mexico. It's a good opportunity to ask them if they have abuelos (grandparents) in Mexico. They might have some relatives living in the Mexico City only three hours by bus from the butterflies. Give your Spanish-speaking students some recognition. Now it's the turn for Mexicans to care for this precious heritage. There are schools near the butterflies your students can correspond with.
Migration--questions and answers
How do the butterflies know where to go? Monarchs use a combination of a "sun compass" for determining direction, along with geographic channeling.
A "sun compass" depends on their internal clock. They have an instinct (internal program) that tells them that that at noon, the sun is in the south, in mid-afternoon, it's in the SW. At sundown, it's a bit S of W. That tells them which way to head.
The overall shape of North America, plus the mountain chain heading south into Mexico, helps refine their direction and channel them to the overwintering area. When they arrive, the area probably feels "just right" to them, so they stop, additionally being attracted to very specific spots by the many butterflies already there.
Some scientists suspect monarchs may be able to sense the earth's magnetic field, but this hasn't been proven.
How long does migration take? From several weeks to two months. They begin migration during September, arriving early in November. (In 2025, the first cluster of migrating monarchs was seen in my areal on August 26.)
Do they migrate at night like some birds? Monarchs don't migrate at night because it is too cold. They are cold-blooded like reptiles. They need the warmth of the sun or air to raise their body temperature to where they can produce the high energy required for flight. They may bask in the sun, shiver, or pump their wings to warm up.
Do they rest along the way? Yes, monarchs rest every night in trees (if available), often gathering in clusters of other monarchs called "roosts." Clusters can sometimes keep them a little warmer, and offer some protection against predators.
How far can they go in a day? A migrating monarch fitted with a tiny radio tags was observed flying 265 miles in a single day. More typically, depending on wind speed and direction, they fly 50-100 miles a day. If the wind is against them, they will fly close to the ground where the wind is slower. They can also fly high, taking advantage of thermals. They are strong flyers that can save energy by gliding.
How late in the fall can they migrate? During migration, monarchs need nectar sources--blooming flowers. The biggest limitation on migration is temperature. They can be released at temperatures above 50 F if sunny, or above 60 F if cloudy. Temperatures only a few degrees below freezing will kill them--and the date of first hard frost in Madison, WI, is October 26. But it's a little more complicated. Frost is more likely at ground level and in low places--monarchs spend the night in trees above the ground, where it may the canopy can also retain some warmth. And as the monarchs move south, temperatures become warmer. Bottom line--the sooner you can release them, the better. As a rule of thumb, don't raise eggs laid after September 20th, and raise them at the highest temperature possible (to speed development).
Why do monarchs migrate? There are two scientific questions implied by the word "why." A scientist would rephrase this question two ways....
What are the advantages to monarchs of migrating? In other words, how does it help the species survive?
The ancestors of monarchs originated in the tropics where they didn't have to deal with the cold. But they could increase the area where they lived, expanding their numbers and range northward, if they could survive freezing. Migration back to the south each year is one way to avoid freezing in the north. So "migration" was an "adaptation" that monarchs evolved slowly over a very long time.
An additional benefit of migration is that the monarchs infected with the OE parasite may be too weak to finish migrating. This helps to reduce the level of OE infection among monarchs. That's the long view of "why" they migrate. Next let's consider the short view, the "why" each individual monarch migrates right now...
What cues stimulate or "tell" a monarch it's time to migrate?
It's actually the caterpillar or chrysalid that decides. Scientists think that declining temperatures, declining quality of milkweed food, and shortening day length are signals that immature stages of monarchs perceive. If the signals are right, the caterpillar or pupa develops into a "migratory" kind of monarch--with more fat deposits (for fuel) and immature reproductive organs (to save weight). When the "migratory" monarchs emerge, it's nearly time to start migrating. The "reproductive" monarchs continue to lay eggs in late August, but some of them also begin to move south, laying as they go. They die of old age long before they can complete the migration. Due to the heavy demands of reproduction, their life spans are far shorter than the "migratory" monarchs which live about 9 months.
Some basic science when you release monarchs
At our release today, someone from a nature center that tags monarchs presented to the students. She explained how they tag monarchs each year and what information this can provide. She showed them how to identify the sex, and let each student place a tag on a monarch's wing. The students were very attentive... they loved it!
Science starts with observation...
- First you observe, then make some generalizations about what you saw. "I saw the butterflies do X when I released them."
- Next, you come up with some ideas (hypotheses) about why they did X. For example, how X might benefit monarchs.
- Finally, you look for evidence for or against your hypothesis. You might get this evidence by making more simple observations, or by performing an experiment.
Here's what you are likely to see upon release, along with possible explanations:
- A few might struggle to gain altitude or land nearby on the ground. These could be too cold to fly, weak because they eclosed several days ago and weren't fed, injured, deformed (due to problems with eclosure), or diseased (OE parasite).
- They circle upward. Circling is a good way to orient and "scope out" nearby resources like wind direction, shelter, or nectar. It's also a good way to gain altitude in an area constrained by buildings or trees.
- They land in a tree, often quite high up. Estimate how high they landed (low, medium high). Trees are safe places for monarchs to rest--and they may need to rest... after all, they have never flown before, or they may be too cold. "You've never flown before. You're in a totally strange situation. Wouldn't it be a good idea to find a safe place to rest and decide what to do next?"
- They land on some artificial object. I have seen them land on a stop sign, a person, and on an electrical wire. I've seen them approach telephone poles but decide not to alight at the last moment. I have no idea if they instinctively avoid artificial objects or people. Possibly they do avoid, since they don't often land on anything artificial. Alternately, they might be attracted to certain features of natural objects such as vegetation. I'm sure they have an attraction to trees.
- Which direction do they fly? They often go SW. But you can't conclude they've already found the direction to Mexico, because they are also attracted to light, and often they are released in the afternoon when the sun is in the SW.
- Rarely, the monarchs might land on a person watching the release. This is more likely, the longer the monarch has been in captivity after emerging. They probably learn the scent of people and learn to associate that with food. They fly to the scent of a person, like a monarch finding a flower.
- They land on a flower to nectar. This is rare. Butterflies are not hungry till the day following eclosure. Even then, not that hungry. Upon release, their need to escape captivity, orient, and rest are much greater than the need for food. If you released them in an area surrounded by lots of flowers, going to flowers might be seen more often.
- They follow (or chase) other monarchs, or land near one. Today I released four monarchs at once. Two of them flew away circling one another, as you often see over a prairie or garden during the summer. During migration and on the wintering grounds, monarchs cluster. I think flying together would be fascinating to study during release. Have four students release their butterflies simultaneously. How many fly together? Land together?
Record some data when you release them
Draw up a data sheet (held on a clipboard). The sheet has space at the top for contextual info like date, time, weather (sun/clouds, temperature, rough wind speed and direction), place, and who is observing.
Decide which of the above behaviors you want to record (maybe add some the students suggest). Draw a separate column for each behavior you are recording, with the first column on the left for the number (1,2, 3...) of the butterfly released and its sex, and the second column for the time released. Each additional column (3, 4...) to the right is for each behavior.
When the butterfly is released, record as a plus, minus, or ?, the behaviors you observed. You might also write (in very small notation) the time the behavior was observed next to the plus/minus/?.
Note: You may need to decide in advance (or after the first few releases) how to better "define" a certain behavior. For example, when I record the direction a monarch adopts on release, I use the direction from release point to the point where it was last seen.
Summarize and discuss your observations
- Which behaviors were most common?
- Did you see any behaviors I didn't list above?
- Did most butterflies do what the students expected? What surprised them?
- Do they think the monarchs decide right away where Mexico is and head that direction?
Of course, you can omit some of the data recording. You can record the contextual info like weather at the end, if everything else went well.
If you release on two different days with different weather (or different times), these conditions might have a big effect on what behaviors you observe. I'd predict that if it was very windy or raining, a larger proportion would quickly land in trees.
The advantage of writing down data, even if it's a bit of work, is that it sharpens your powers of observation. And it forces you to define what you really mean by "going in a certain direction."
And if you should see something really interesting--like all the butterflies you release at the same time flock together-- usually you can't remember the interesting details after the fact. It's lost! You could have discovered something new to science--but nobody is going to believe you because you didn't write it down.
Equipment suggested for release activities
- Map of North America !!!
- Photo of tree covered with monarchs in wintering area
- Thermometer for place where butterflies are held before release. They won't fly if cold. Needed only if you suspect the temperature where butterflies were kept before release is sub-optimal.
- iPhone to get wind direction, wind speed, and outdoor temperature before release.
- Paper, pen, and clipboard for recording data.
- Monarch tags and data sheets (optional)
- Mesh container for transporting monarchs from classroom to release point
- Honey (and floral tube or small bottle) for feeding monarchs, diluted to 20%
- Q-Tips for feeding monarchs