Caterpillars, Butterflies and Transformation

One of the most spellbinding few hours I have ever spent was when I watched the emergence of several monarch butterflies from their chrysalises anchored to a bouquet of milkweed at one of our past Bugfest events. Somehow, I had managed to get through my childhood, and much of my adulthood, having never had such a treat. Oh, sure, I knew about it. I was well-versed on the stages of butterfly metamorphosis. But it was another thing entirely to observe each green chrysalis up close, as it slowly became transparent, revealing the black and orange wings of the insect inside. Finally, the insect would manage to break free, so fragile and trembling, pumping fluid into its expanding wings and preparing for a first flight. How does one possibly witness a thing as this, and not be equally transformed?

Michael Olive watches a monarch butterfly as it emerges from its chrysalis during the Crosby Arboretum’s Bugfest event

Throughout my time at the Crosby Arboretum, I have spoken with many parents and teachers who have enjoyed raising caterpillars into moths or butterflies, to the delight of fascinated children. This is a simple, inexpensive way to provide an educational experience that can remain for a lifetime.

The Arboretum’s travelling educators’ box on the topic of insects contains two excellent books on the subject of keeping insects for observation: “Pet Bugs: A Kid’s Guide to Catching and Keeping Touchable Insects”, and “More Pet Bugs”, by Sally Kneidel. Both of these books will provide great winter reading and are currently available for only a penny each (plus shipping) on the popular book sites that also offer used book sources.

You may search for caterpillars in your local field or forest. However, when you find a caterpillar, pay attention to the surroundings, as the chances are good that the plants you discover it on, or near, will be its “host plants”. If you prefer a particular butterfly, find out what its preferred host plants are. For example, gulf fritillary caterpillars feast on passionflower vines, and milkweed is the host plant for the popular monarch butterfly.

It is important that you make a positive identification of your caterpillar, so you can provide him with the food he needs. If you are not sure of its species, it would be best to let it go because the insects are very particular about the food they consume.

This week, our new senior curator Richelle Stafne found a caterpillar that at first glance appeared to be a luna moth. The head and body certainly resembled the photos we found. However, she observed that the caterpillar in the photos lacked the purple marking found on her caterpillar. As caterpillars will pass through a number of stages, called instars, it seemed possible that it might currently be lacking some characteristic. Based on thinking this was a luna moth, we gathered sweetgum, maple, and beech leaves.

A day later, further research revealed that the caterpillar was instead the larval stage of a polyphemus moth. Preferred food luckily included the maple leaves we had gathered, but other common host trees were cherry, oak, and willow. But on Sunday, the caterpillar solved the food problem and spun a cocoon. Polyphemus moth caterpillars go through multiple generations from May through October. Some will overwinter. Since this one was discovered late in the season, he will be kept outside in order to avoid the chance of emerging in a nice warm house, only to search in vain for a mate.

There are many containers suitable for rearing caterpillars, such as a spare aquarium with netting over the top, or special collapsible butterfly cages. Add sticks to the container so the caterpillar can use them to pupate (turn into a chrysalis). It is also a good idea to consult websites on the Internet to learn in more detail the process for rearing butterflies, or to order chrysalises. For example, caterpillars usually like more humidity than found indoors, and a misting bottle may be used. But, too much water can cause bacterial growth.

Another simple way to contain caterpillars is to modify a container such as a glass jar, using aluminum foil over the mouth, or a margarine tub with holes punched in the lid. Place water in the container. With pruning shears, cut stems of the plant desired host plant material at a sharp angle for maximum exposure to the water. Place the cuttings into the holes. Don’t let the leaves touch the water (to avoid decay). Tightly cover the mouth of the container, to prevent the caterpillar from falling into the water.

Purchase a yard or so of netting at the fabric store and drape this over the plant material. Use a rubber band to attach the netting around the base of the container. The netting is easily removed to clean out the droppings daily that will collect in the bottom as the caterpillar feeds. It is important to keep a fresh supply of cuttings available for the caterpillar until he begins to pupate. This method would work well for monarch caterpillars, however, for luna moth caterpillars or other caterpillars in the Saturniidae family, it is best to maintain an aquarium with a carpet of leaves to replicate the forest floor, as these caterpillars often pupate in cocoons that are rolled inside leaves on the ground.

Come take a walk at the Crosby Arboretum soon, and enjoy the cooler weather. For more information, please see our website at www.crosbyarboretum.msstate.edu, or contact the Arboretum office at 601-799-2311. We are open Wednesday through Sunday from 9 a.m. to 5 p.m. and located in Picayune, off I-59 Exit 4, at 370 Ridge Road (south of Walmart and adjacent to I-59).

For further exploration

1) What does a Polyphemus moth look like? Search the Internet for a photo. You are really in for a treat.

2) What other moths are found in the Saturniidae family?

3) Make a list of area butterflies or moths that you find particularly fascinating. What plants do their caterpillars eat? Learn how to identify, and locate, these plants. Make a plan to search for them, and raise them, next spring.

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