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Meet The IO Moth, Active Now Locally

By Adrian Newby

    Who doesn't love learning? We all enjoy finding out about new things and sharing them with others, but sometimes we don't know where to start. That is the spot we were in when we began working on this article. We weren't sure what direction to take it in, so we just stared out the window. While we were distracting ourselves, we noticed some large green caterpillars that we didn't recognize on a crepe myrtle just outside our window. Naturally, we had to look them up.
    We started by simply looking up “large green caterpillar with red and white stripe”, and found out that our little garden guests were the final pre-metamorphosis form of the Automeris io moths (also called Io moths). These moths can grow to have a wingspan of just over three inches, and will be yellow and brown as adult moths; with the males being brighter and more yellow.
    They can be found in about 43 of the United States. They can be found from as far north as Canada at Lake Huron to Ottawa and down to Hamilton, and down the Atlantic coast as far as Merida in Mexico, and then as far west as Utah and Montana.
    The caterpillars we found were fully-grown Larvae. Soon they will begin spinning their thin little cocoons and start their two-to-three-week metamorphosis into moths. This is the end of their life cycle though, so we should probably jump back and talk about how it all starts.
    An average batch of Io moths numbers at about 20 eggs. At about eight days old the eggs’ appearance will begin to change, growing from green to a darker yellow. Soon after this change, a small red caterpillar with black spines will hatch from each egg. The freshly hatched larvae will begin to quickly devour their host plant, quickly growing and gradually turning yellow. They will then change from yellow to bright green, and they will get a red and white stripe down their side. This is the final color of their larval life, and they will then eat until they are ready to spin a cocoon and morph into their new form.
    In two or three weeks when their metamorphosis is complete, they will emerge from their cocoons and begin their four-to-fourteen day life. The males will come out with bright yellow wings, with red and brown patterns including two large black spots on their small wings. The females will be brown in color with black and yellow patterns, and the same two black spots.
    Like most moths, they are harmless and the only threat they pose is to a few leaves on the broadleaf plants which they hatch on. Two of the common host plants for the Io that you may have in your yard are the crepe myrtle and the pear tree, so take a look in your yard and you might get to see some of these beautiful little moths before their cycle starts over. The caterpillar stage is certainly impressive and was cool enough for us to want to know what it would become next.