Rearing North America’s largest moth

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Caterpillar of the cecropia moth, Hyalophora cecropia (Kennebunk, ME)

Almost immediately after finding the northeast’s rarest waterscorpion, my dad alerted me to a “really cool caterpillar” just a few steps away. When he pointed it out to me I was stunned–a cecropia moth caterpillar! An iconic species, Hyalophora cecropia is considered to be the largest moth in North America, with an equally large caterpillar. But they are not just large–they are absolutely beautiful in all stages. Caterpillars are plump green monsters bristling with red, yellow, and blue scoli (knobs with spikes), and the adults are an unbelievable mixture of reds, browns, pinks, and creams, one of the most charismatic moths out there and a perfect example to point to when people say that moths aren’t as beautiful as butterflies. I had only seen three adults in my life and never a caterpillar, so I was pretty dang excited about this one.

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The resulting moth.

After I had taken the caterpillar home and photographed it, I set up an enclosure with lots of food. The ‘pillar was originally on speckled alder, but I found that it would accept maple as well. The next day the leaves were gone, converted into a pile of frass at the bottom of the container, as any self-respecting caterpillar tends to do. This continued for several weeks, with daily replacing of the food and emptying of the waste a necessity for the caterpillar’s survival. Strange as this may sound, I found the frass pellets to be little works of art, intricately marked with lines and spots. Unfortunately I never thought to take a photo. Eventually the caterpillar pupated in a huge baggy cocoon, and into the garage it went to overwinter.

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What a wondrous sight to wake up to!

One lovely day next June, I found that the adult moth had emerged. The first thing I did upon seeing her hanging upside down in the rearing cage might seem a bit odd: I bent down and sniffed her. Something I have experienced with every cecropia moth I have encountered is that they smell very strongly of peanut butter! I initially thought this was just the female’s pheromones, but I have smelled it on males as well. It was a miracle that the caterpillar had not been parasitized by flies or wasps, as many such large caterpillars often are. My moth was a female, as evidenced by her plump abdomen full of eggs and her slender antennae (males have large feathery antennae to detect the pheromones of the female). Cecropia moth adults have no functional mouthparts and only live long enough to reproduce, so the next day my dad and I took her back to where we found the caterpillar and released her deep in the bushes, where she hopefully attracted a male and laid eggs to bring about the next generation of these spectacular insects.

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Detail of the abdomen.

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