Studying Monarch Butterflies
This fall, the Autumn Room at Inver Glen began the year with a study of monarch butterflies. We observed caterpillars from the time they were scarcely big enough to be seen without using a magnifying glass until they were beautiful orange, black, and white butterflies ready to be released into nature.
Throughout our study, we read books about the life cycle of the butterfly, learned new vocabulary, and created art projects that introduced concepts such as patterns and symmetry. Each day there was something different to see: the caterpillars grew quickly, and as their bite marks in the leaves grew larger, so did the frass (insect poop) littering the cage floor.
The monarch caterpillars arrived the first week of school already in their larva form. We ordered the rearing kits from a nonprofit program based out of the University of Kansas called “Monarch Watch.” As soon as the larvae arrived, we carefully transferred them using a small, fine-bristle paint brush, to fresh, clean milkweed leaves, preferably ones grown away from pesticides or other treatments. The larvae are so small, it takes some effort to locate them in their containers. The children quickly learned that the caterpillars need milkweed to survive, and going on milkweed hunts became a common part of our time at school. The children even learned to identify and point out milkweed plants on their own.
When the caterpillars were small, we kept them in clear plastic storage containers with removable mesh screens. The children observed the caterpillars using magnifying glasses. The caterpillars spend their days consuming milkweed and rapidly grow bigger, eventually increasing their size by 2000%! As the caterpillar grows, it sheds its skin. First, the caterpillar appears light green with a black head. Its jaws are so small it can only eat the top of the milkweed leaf, which is quite tender. Soon, as the caterpillar grows and molts, the distinctive yellow, black, and white stripes become visible, and it starts to eat the side of the leaf. The children loved watching their little mouths chomp away at the leaf, creating holes and visibly chewed edges. As the caterpillars grew, we transferred them to butterfly cages with large stalks of milkweed in vases. The children arrived each morning exclaiming in surprise at how big they had grown and excitedly pointing out the frass on the leaves and bottom of the cage. Some days the children could find the discarded skin after a caterpillar had molted. We cleaned the cage and changed the milkweed often, ensuring there was enough for the caterpillars to eat and that it stayed fresh.
Two to three weeks after we received the caterpillars, they began to climb to the top of the cage or the underside of a leaf where they hung upside down in a J formation, held securely by a silk button they weave. They hung upside down for about 24 hours until they molted for the final time, forming their chrysalis. One afternoon, after the class had left, the teachers and some students from a different class were lucky enough to observe some of them forming chrysalides, and we caught it on video. We emailed the video to the families so they could watch it with their children. The caterpillar skin splits at the head, and it starts wriggling, causing the skin to bunch up at the top of the J near the silk button. Underneath is a light green pupa, which slowly hardens and forms into a stunning chrysalis, hanging from a black string called the cremaster, which is attached to the silk button. Once complete, it is a beautiful jade green with gold specks on it. It almost looks like a pendant one would wear as a necklace!
The students were so excited to see the chrysalis the following morning and had a lot to say about it: “It is so green!” “Wow, that’s AMAZING!” “Look how small it is!” “The caterpillar will be a butterfly now!” Each morning the children entered the classroom to find more and more chrysalides having formed, with sixteen total. Unfortunately, our final caterpillar, which would have been our 17th, ran into trouble while forming its chrysalis and it was obvious right away that it wasn’t going to make it. We explained that sometimes this happens in nature; things don’t always go as planned. We decided to bury the chrysalis in our playground garden where milkweed grows. Some students helped dig a hole and lovingly placed it inside before covering it with soil and rocks that they decorated with chalk. They expressed sorrow for our chrysalis that would never become a butterfly. We explained that the buried chrysalis would break down and become part of the soil. That soil will help the milkweed plants to grow which in turn will help future butterflies.
About two weeks later the butterflies were ready to emerge. The wing pattern of the butterfly becomes visible as the chrysalis becomes transparent, and you can see the butterfly folded up inside. We caught one emergence on video and were able to observe the butterfly immediately afterward. The children were surprised that the wings were so small and crumpled up and the abdomen was so swollen. However, it didn’t take long for the fluid from the abdomen to be pumped into the wings, causing them to stretch out. We were careful not to disturb the butterfly cage at this point because the butterfly could not yet fly. The wings needed to fully dry out while the butterfly hung upside down. Some children even saw the proboscis curl and uncurl as the butterfly got used to its new form. Eventually, it started opening and closing its wings and that is when we could identify if it was male or female. We made a chart of how many of each we had, including our guesses and the actual number. The children knew that if the butterfly is male, it would have two black dots, one on either wing. This gender reveal was especially exciting for the children to discover, and they would gleefully jump up and down announcing, “It’s a boy!” Or “A girl! A girl! It’s a girl!” We ended up with eight females and eight males.
Finally, it was time to release our butterflies into nature. We waited for the weather to be warm enough, and the children dressed in large monarch wings they had decorated themselves. We brought the cages outside, and if we were lucky, the butterflies would let us hold them before we either transferred them to a flower or they flew away. The children, dressed in their wings, chased, and waved goodbye to them while blowing kisses and wishing them good luck on their long migration. It was the perfect ending to a rich experience and a celebration of the magic of nature.