NORTH AMERICA’S STUNNING AND LARGEST MOTH THE CECROPIA AND WHY THESE GIANT SILK MOTHS ARE THREATENED – PART TWO
After spending the winter and most of the spring tightly wrapped in their cocoons of spun silk, the first male eclosed on the last day of May. Burly and beautiful, Cecropia Moths emerge with wings patterned in white crescent spots outlined in rust and black, sapphire blue and black eyespots, waves and wiggly lines in soft woodland hues, and a wide tubular body banded and dotted orange, black and white.
It is easy to tell the difference between a male and female because of the male’s spectacular plume- like antennae.
After each Cecropia Moth emerged from its cocoon and their wings had dried, we placed them on the shrubs around our front porch. The males eventually flew off, but the females stayed in one place and usually by morning we would find a pair, or two, mating in our garden.
I had read it only takes a week or so for the larvae to emerge from their eggs and was beginning to think ours were not viable, when they began hatching today! In actuality it really took between two and three weeks for the caterpillars to emerge. Possibly the cooler temperatures during this period slowed hatching. The caterpillars are teeny tiny, perhaps one quarter of an inch, black with pokey spines. Charlotte and I collected a bunch of Chokecherry (Prunus viginiana) branches this morning as we prepare to raise another batch of stunning Cecropias.
The adults, both male and female, are short lived. Giant Silk Moths, which include Luna, Polyphemus, Promethea, and Cecropia emerge without mouthparts and cannot eat. Cecropia Moths spend several months in the larval stage, most of their lives as a cocoon, and only a week or two as their beautiful winged adult selves. Giant Silk Moths live only to reproduce.
Threats to Giant Silk Moths are significant. The number one threat is Compsilura concinnata, a tachinid fly that was introduced to North America to control invasive European Gypsy Moths. Both insects are a cautionary tale of why not to introduce invasive species without knowing the full breadth of the harm they will cause. Spraying trees with toxic pesticides that kills both the caterpillars and the cocoons is also a major threat. And, too, squirrels eat the cocoons
Hyalophora cecropia moths are univoltine, having only one generation per year. Our Cecropias began hatching just before the full moon. I have more cocoons and am wondering if this next batch of moths are waiting to emerge prior to July’s full moon.
Last summer my friend Christine gave me a handful of Cecropia Moth eggs. Nearly all hatched and grew, AND grew, AND GREW. The caterpillars were a whopping five inches in length and the width of a very large man’s thumb before they began to pupate (become a cocoon).
The Cecropia caterpillar eats the leaves of many trees and shrubs, including alder, ash, birch, box elder, Chokecherry, elm, lilac, maple, poplar, Prunus and Ribes species, and willow. People are always a bit dismayed when I tell them that the adult is born without mouthparts and cannot eat during its brief lifespan. The adult’s only purpose in life is to mate and it lives for about a week or so.
We fed our Cecropia caterpillars Chokecherry (Prunus viginiana), because I knew of a good source where it was growing plentifully.
Cecropia Spinning a Cocoon -The caterpillar pulled some leaves loosely around, but mostly the cocoon is made from its own spun silk. Some spin their cocoons on tree branches and some on the sides of the buildings.
All winter the cocoons lived in glass terrariums on the side of our front porch, which is not enclosed, and which is also out of direct sunlight. The cocoons need to experience normal fluctuations in temperature so that adults will emerge at the correct time of year, when trees are leafed out.
Cecropia Moths are the largest moths found in North America. They are members of the Family Saturniidae. There are approximately 1,500 species of large moths in this family and they are found all over the world. The very largest are found in the tropics, but the wingspan of our Cecropia Moths can reach an amazing 7 inches across (compared to a Monarch, with a wing span of approximately 3.5 inches).
Part Two – emerging, reproduction, laying eggs of the next generation, and how we can help this increasingly rare species.
From the tiniest pinhead-sized eggs hatched quarter-inch caterpillars. A month later and these gorgeous Cecropia Moth caterpillars (30!) are approximately five to six inches in length and 3/4 of an inch in diameter.
Noticeably growing larger day by day, the biggest caterpillar of our batch of Cecropia Moth caterpillars (nicknamed Mothra) still has a ways to go before he/she pupates and becomes a cocoon for the winter.
The colorful protuberances with black spikes are thought to mimic either a poisonous plant or animal and are a defense against predators. Like most caterpillars, the Cecropia moth caterpillar has five pairs of prolegs. The green prolegs are blue at the base with a row of microscopic hooks, or crochets, that enable walking and clinging.
Although the Cecropia Moth has the largest wingspan of any moth found in North America, its caterpillar is not the largest caterpillar. That honor goes to the caterpillar of the Royal Walnut Moth, also called Regal Moth, which in its caterpillar stage is called the Hickory Horned Devil.
Thank you again to friend Christine for the Cecropia Moth eggs. The eggs that she gave me are the offspring of the male Cecropia Moth that she is holding in the photo above.
Don’t you love the colors of the third stage, or instar, of the Cecropia Moth caterpillar? Only about an inch and a half long in the photo, in the final fifth instar, before it pupates into a cocoon, the caterpillar will be as large as a large man’s thumb.
In its second instar in the above photo, the caterpillar resembles the developing birch flower catkins. This is an evolutionary form of mimicry against predation by birds. Cecropia Moth caterpillars eat not only the foliage of American White Birch trees, but also other species of birch trees, apple, ash, beech, elm, lilac, maple, poplar, Prunus and Ribes species, white oak, and willow.
Thank you so much again to my friend Christine for the gift of the Cecropia moth eggs.
This newly emerged Cercropia Moth, the largest species of Lepidoptera found in North America, was photographed at the home of my new friend Christine. She lives on the backshore of Gloucester and, with her friend Jane, who lives on the opposite side of Gloucester in the Lanesville area, are trying to repopulate Cape Ann with several species of the stunning and charismatic moths of the Saturn Family. These include the Cecropia Moth (commonly called Robin Moth), Luna Moth, and Polyphemus Moth.
Where formerly abundant, these most beautiful members of the native Giant Silkworm Moth group of Lepidoptera are at extreme risk of becoming extirpated (extinct from a region). Christine recalls a time when she could easily find the cocoons in her neighborhood. Now she finds none. The reasons for their decline are severalfold; loss of habitat, the poison in the pesticides sprayed on trees is highly toxic to all insects, and because they are suffering from a parasitism by a tachinid fly (Compsilura concinnata) that was introduced to control the Gypsy Moth. Each and every person on Cape Ann can help these moths make a comeback by making a commitment to not use pesticides and herbicides, for any reason, ever.
Christine and Jane purchase the cocoons at Magic Wings in Deerfield, MA. They place the cocoons in the screened butterfly house where they have also placed branches of the caterpillar’s food plant (in this case, birch branches). Cecropia Moth caterpillar food plants include the foliage of maple, birch, ash, apple, cherry, and lilac.
If both male and female are present, they will mate almost immediately, within the first day or two, and the female will begin depositing eggs soon after. She releases the eggs on nearly every surface within the enclosure, dozens and dozens of eggs, up to 100!
If the eggs are viable, within several weeks, the caterpillars will chew their way out of the egg casing and begin to eat the caterpillar food plants provided.
Perhaps like Christine and Jane who, moth by moth, are trying to save our native Giant Silkworm Moths, you’ll be inspired to raise these North American beauties, too!
More photos to come if a batch of caterpillars emerges.
Lecture Tuesday night, April 9, at 7:30 at the Manchester Community Center: Oh Garden of Fresh Possibilities! ~ Notes from a Gloucester Garden.
Cabbage White Butterflies Mating in the Native Flowering Dogwood Foliage
The lecture tonight is based on the book of the same name, which I wrote and illustrated. In it I reveal how to create the framework, a living tapestry of flora, fauna, and fragrance that establishes the soul of the garden. Using a selection of plant material that eliminates the need for pesticides and herbicides, and guided by the plants forms, hues, and horticultural demands, we discuss how to create a succession of blooms from April through November. This presentation is as much about how to visualize your garden, as it is about particular trees, shrubs, vines, perennials, and annuals. Illuminated with photographs, and citing poetry and quotations from Eastern and Western cultural influences, this presentation engages us with an artist’s eye while drawing from practical experience.
For a complete lit of my 2013 – 2014 programs and workshops, visit the Programs and Lectures page of my blog.
The Cecropia Moth, or Robin Moth (Hyalophora cecropia) is the largest moth found in North America, with a wingspan of up to six inches. He is perched on the foliage of our beautiful native Magnolia virginiana (Sweetbay Magnolia), one of several of the caterpillar’s food plants. You can tell that he is a male because he has large, feathery antennae, or plumos, the better for detecting scent hormones released by the female. This photo was taken in our garden in early June.
The Manchester Community Center is located at 40 Harbor Point, Manchester.