The Beautiful IO Moth
One day on a beautiful early fall afternoon we were taking a
stroll across campus. We had just escaped an extra credit seminar on dental
hygiene school, so it was safe to say we were ready for some interaction with
nature. On our sunny walk, we heard a girl gasp with excitement as she stared
into the palm of her hand. Driven by curiosity we hurried over to see what had
caused the commotion. It was a beautiful green caterpillar. It was unlike
anything I had ever seen, it was bright lime green with bristles covering its
body. It was curled up in a defensive posture. This position revealed a crisp
red over white line that ran laterally along its body.
The girl’s excitement transferred
over to us as we examined this cool creature. This caterpillar was interesting
to use because we were in the midst of an insect ecology class where we have to
collect and maintain an insect collection. The immediate thought across our
minds was to figure out what kind of Lepidopteran it was and try to rear it.
Guessing from its vibrant colors, we knew it was likely dangerous. Many insects
employ this type of defense system when they eat toxic plants, they show
vibrant colors as a warning to predators. As we examined it further, our
thoughts were proved true…. Grayson’s hand began to grow numb as its defense
mechanism kicked in. After placing it in a box, we fired up the old faithful
search engine, Google. We searched bright green caterpillar and the IO moth
popped up immediately (https://www.kplctv.com/story/22976957/warning-about-io-moth-caterpillar-stings/). We began to read about the creature learning about its
powerful stings, rashes, and hives a brief touch can cause.
Unsurprisingly, the moth is native to Oklahoma, as well as most of the eastern United States. For the last 50 years, they have been known as a declining species. Being under decline, the IO moth, now more than ever needs to defend itself. To quickly highlight some of the defenses the caterpillars have, they dominantly use coloration and their venomous spines. Many predators of the IO moth will distinctly recognize their color and will remind these predators that they (hopefully) had a poor encounter last time and will leave the caterpillar alone. The IO moth caterpillar also has the green spines visible in the image above. These spines have small black tips on the ends of each that when touched, will remain in the attacker. These spines have been medically observed to lay on the inflammatory border line. In simpler terms, they will typically cause inflammatory problems, but due to how small these tips are (12 micrometers), in some cases there is no swelling whatsoever. The venom of the moth has been described as much more painful than a bee sting. In humans, itching will typically follow the pain and a welt will form. Its sting has been tested against a rabbit, hamster, and mouse, and these animals yielded no reaction.
In comparing the first image to the second, there is a lot of observable difference between the two. This is because of its development, and there are reasons the moth does not keep its green color. In development, the eggs will begin white with yellow spots. These eggs hatch and give way to a small orange larva with small spines. With each stage of molting after the first, they become more yellow, then more green. In its last stage of molting, the caterpillar will become the green form we know of with red and white stripes down its side. When it is time to cocoon, it will begin to form silk in a clutter of leaves. The cocoon will turn brown and harden, then will remain this way until the moth breaks through. The female moth will be a yellow color as the image shown, and the males will be slightly more orange. This coloration is used to blend in to dead leaves in the forests that they predominantly live in. The "eye" coloration on the hind wing is characteristic to the Automeris genus which contains 145 different species. When perched on the ground or in leaf clutter, under distress, the moths will show their eye patterns in upright form. This is a defense predominantly against birds and some other predators, imitating the reflection of vertebrate eyes.
Many caterpillars and mature Lepidopterans are very distinct from their relatives. Anyone who has come in contact with this caterpillar will never forget it. I know I will never forget my hand going numb and beginning to feel a stinging sensation in the middle of my palm. Personally, I do not enjoy that feeling and many other predators don't either! The IO moth is a beautiful organism but should also be adored from a distance.
We used the website http://entnemdept.ufl.edu/creatures/misc/io_moth.htm for a lot of our helpful information on the IO moth. It includes a lot of developmental pictures and interesting facts about the moth.
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