“Butterflies for Science?” was the invitation I emailed my friend.
“YES!” she answered, “I want butterflies for my classroom. How do we do it?”
Here’s how we DON’T do it:
No kits of generic caterpillars mailed 2nd Day Air with tubs of larval food paste (a “proprietary mixture of vitamins, proteins, and fats”).
No butterflies released into the wild without regard to the calendar or what plants are outside.*
Our butterflies are a name brand! The Gulf Fritillary.
Our caterpillar food is the real thing, the ONLY thing: this butterfly’s particular larval host plant. There would be no new Gulf Fritillaries without it.
To be clear: adult Gulf Fritillaries can eat nectar from many species of flowers, but “baby” Gulf Fritillaries—the caterpillars / larvae—can *only* eat leaves of native passionvine.
To show the process of Complete Metamorphosis
by showing a butterfly’s life cycle on its native host plant,
within the context of our local habitat,
and in the “natural” time of year.
So, my friend let me bring to the science lab:
-A purple passionvine (Passiflora incarnata) in a pot (with a flower and fruit).
-Gulf Fritillary caterpillars on the plant, from egg to final instar (big teenage caterpillars ready to pupate).
-Chrysalids / Chrysalises soon to emerge as adult butterflies.
The plant sits on the counter, so caterpillars are up-close and personal. Students can watch them eat and poop and molt.
And behind the plant is a huge window. When a butterfly emerges from a classroom chrysalis, the teacher opens the window so students can watch the brand-new, adult butterfly flutter to freedom.
Outside, the butterfly will find more Gulf Fritillaries and more passionvine, because older students have planted a whole bed of passionvine on the Green Roof.
The plant is the key difference between most butterfly kits and Real Life.
As if watching a caterpillar become a chrysalis isn’t enough of a miracle,
as if watching a chrysalis become a butterfly isn’t enough of a miracle,
we get the Big Picture of what makes these miracles possible: “larval host plants.”
No passionvine = no Gulf Fritillaries.
Just like no Milkweed = no Monarchs,
and no Pawpaw = no Zebra Swallowtails,
and no Pipevine = no Pipevine Swallowtails.
And so on, and so on.
Most insects have evolved to eat specific plants so that they can survive and reproduce.
Our butterflies aren’t the exception: they are the rule.
This is my favorite way to introduce people to the idea of “host plants,” and Why Native Matters.
And for this experiment, I don’t even do the introduction, I just supply the setup. A master teacher takes care of all the teaching, while I sneak in every now and then to make sure the plants and animals are happy.
Here are some updates from the teacher:
“It’s the greatest! So many questions! The kids are loving it! I cannot use enough exclamation points!”
“…the butterfly in the little enclosure started eclosing right at the beginning of break and completed the process (just the emerging, not the meconium) right at the end of break with about 25 kids (some squealing, some awe-struck) riveted to the process. We released it about 15 minutes ago. Pure magic.”
“Don’t worry about the frass. We talk about poop all year. It’s an important part of life.”
“Butterflies eclosing, kids releasing them, three squealing science teachers watching the formation of a chrysalis. Lots of people dropping by to take the Gulf fritillary tour.”
“We’ve now released 7 butterflies, and I’d say we had at least 20 caterpillars we observed eating & growing with over a dozen pupating.”
“We had over 100 students take the butterfly tour, and we had about a dozen faculty over and above that. They learned what “frass” and “eclose” and “chrysalis” and “J” and “meconium” and “metamorphose” and “pupate” mean with respect to butterflies, and they saw the life cycle of the Gulf fritillary from egg to death. [There is a preserved specimen on display.] I’ve got 8th graders who come in regularly to try to catch an event!”
. . .
How to replicate:
This experiment is possible because 1) the teacher is stellar and 2) I have access to a lot of passionvine, which attracts a lot of Gulf Fritillary action. At home, I get to see butterflies feeding, cruising, mating, laying eggs all through summer and early fall. Every day is Butterfly Day.
Purple passionvine (Passiflora incarnata) is the Tennessee State wildflower, and it grows wild state-wide. We also have the little yellow passionvine, Passiflora lutea, but while it is a Gulf Fritillary host, the leaves (and flowers) are smaller, and it is harder to find enough to support a big group of caterpillars.
Other host plant and caterpillar demos are possible where there is a sure, local supply of both. Monarchs and milkweed would also be ideal, but I haven’t found enough caterpillars at home or at our Green Roof’s “Monarch Way Station” to make this possible.
Admittedly, there is one stage of life cycle the classroom does not get to see: Mating.
In order to make that possible, we’d have to keep butterflies captive in a cage, and we aren’t willing to do so. We want the butterflies to be freeeeeee.
But ideally, mating would be visible on the school’s Green Roof, where passionvine and nectar flowers act as both a family buffet and a singles bar.
*”Generic” kit butterflies are usually Painted Ladies, a species with a wide geographic range, and a wide range of host plants, but the food paste shipped with the larvae means that a kit demonstrates no connection to real-life food or habitat.
And every summer and fall my Instagram posts include a lot of Gulfie and passionvine action.
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Joanna Brichetto is a naturalist and writer in Nashville, the hackberry-tree capital of the world.
She writes about everyday marvels amid everyday habitat loss, and her essays have appeared in Creative Nonfiction, Brevity, Fourth Genre, Hippocampus, The Hopper, Flyway, The Common, Stonecrop Review, The Fourth River and other journals. Her almanac of local urban nature stories is forthcoming.