Mammoth Moths: Cecropia Moth
The Great Outdoors | July 5, 2023
By Jackie Scharfenberg, Forest Naturalist, Wisconsin Department of Natural Resources
I was munching away on some maple leaves when I heard a loud scream.
I thought something tragic had happened, but no! It was a kid who thought I was a space invader!
Our Appearance
We cecropia moth (Hyalophora cecropia) caterpillars grow quite large – up to five inches long and
as round as an adult human’s thumb. We start as tiny black caterpillars and as we grow through five molts (instars), we change in color from black to yellow to blue/green. As mature caterpillars, we sport very colorful, spiny tubercles (knobs) – two rows of blue ones along each side, two rows of yellow tubercles down our backs, and two large pairs of red/orange knobs on our thoraxes.
Our Wings
After pumping up our wings and bodies, our wingspans can reach five to seven inches (bigger than most adults hands) making us the largest moths in North America. Our reddish fuzzy body includes a white collar and white bands on the abdomen. Our large scale-covered black to brown wings are surrounded by a border of white, red, and tan stripes. Each of our four wings has a crescent-shaped white spot outlined in red.
Our Diet
As young caterpillars we feed in groups on leaves of various trees and shrubs such as box elders, sugar maples, wild cherries and plums, apples, alders, birches, dogwoods, and willows. We are not picky eaters. As we get older, we head off to become more solitary feeders.
Cocoon Life
After four to nine weeks, we seal ourselves into silky cocoons attaching them lengthwise to twigs. The cocoons start out red/brown in color and then turn gray with age. We try to construct them in dark, protected areas to avoid predation by rodents like squirrels and birds. We spend the entire winter in our cocoons, emerging with the warmth of spring as full-sized flying adult moths.
Our Short but Purposeful Life
Adult cecropia moths only live two weeks. They lack functional moth parts and digestive systems. Our mission as adult moths is to mate so the females can lay their eggs. To find a mate, females release a scent, a pheromone, that the males can detect with their antennae from over a mile away. WOW! A pair will start mating in the early morning and continue until the evening. After mating the females search out host trees and shrubs. They will lay more than 100 eggs in rows of two to six on both sides of the leaves. After 10 to 14 days, the tiny caterpillars hatch from the eggs.
Each year we produce only one generation with the adult moths emerging the first two weeks of warm weather in spring. On one of those warm spring evenings after dark, head outside to search for us adult moths. We are attracted to streetlights and other outside lights, making those good places to search for us. Check out young trees and shrubs in your neighborhood for our large, colorful caterpillars! Maybe you can spot one of us mammoths of the moth world.
