For anyone that raises butterflies and moths, having your caterpillars form pupae is a huge undertaking. You spend weeks feeding these hungry mouths and though you may be doing it in protected environments, the chance of failure is still there. Stink bugs, yellow jackets, skunks and raccoons are always hungry for your babies and at times, no matter how hard you try, they still seem to find what you are working so hard to protect. There is an excitement that is unequaled when your caterpillars finally form their chrysalis or cocoon. With all of these odds against you in captivity, what chance do they have in the wild?
I think this is why when I actually find a chrysalis or cocoon in the wild, it is even more exciting. From the moment a caterpillar eats its way out of its tiny egg the odds are stacked against it. Even if they make it to the pupal stage they still risk being parasitized by wasps or being found by birds or mammals looking for a meal.
Finding chrysalises and cocoons in the wild is very difficult because in most cases, they rely on camouflage to help them survive the long winter. In the case of moth cocoons, with emphasis here on those in the Saturniidae family, they often hide themselves within leaves, hoping to survive until the next spring.
For this blog I will be concentrating on five of the most popular Saturniid moths from the Eastern United States. I will describe not only what to look for, but also where the best places to look will be. For a list of the foodplants used for each species, please read my blog on Saturniidae foodplants HERE. Finding cocoons is a skill and I know some people who rarely find them in the wild and others who can find them every time they venture out into the woods. The key is to know the foodplants of the caterpillars and to know what these plants look like in the fall and winter.
Actias luna (The Luna Moth): this is perhaps the most beautiful of all of the North American moths, with its lime green coloration and long tails. The cocoon is thin and if held up to a light, the pupa can oftentimes be seen within. It is brown in color and is usually spun within a curled leaf of the foodplant, later to drop to the ground when the leaves fall from the trees at the end of the season. Caterpillars may also climb down to the base of the tree to build their cocoon. As the rest of the leaves fall, they provide insulation for the cocoon for the cold winter months. There is no discernable peduncle (silk used to attach the cocoon to a branch often incorporating parts of the branch in its construction). The pupa is very active within its cocoon, with the abdomen violently shaking back and forth when disturbed. These cocoons are easiest to find before the leaves drop to the ground, especially if they are still green as the brown silk is an obvious contrast.
Antheraea polyphemus (The Polyphemus Moth): this large moth is best known for the large eyespots on its hindwings, used to scare off potential predators. The cocoon is egg shaped and very solid. Sometimes it is formed with a peduncle and can be found hanging from a branch and other times it will be wrapped in a leaf, to fall to the ground when the leaves drop in the fall. The cocoon is a light tan in color and if the dead leaf is peeled off of the cocoon, the negative of the leaf will be on the surface of the cocoon. There is no valve present so when it comes time to hatch, the moth must secrete an enzyme to soften up the end of the cocoon so that it can escape. They are easiest to find before the leaves fall off of the tree, as their color contrasts the leaves really nicely.
Automeris io (The Io Moth): this small, but beautiful moth, also features large eyespots on the hind wings and feature sexes that look different from each other (males are smaller and yellow and females are larger and more of a pinkish-orange color). The cocoons look like a smaller version of those of Actias luna. They do not have a peduncle and are either formed within the leaves of the foodplant or at the base of the tree. Unlike the luna, the pupa within is not active if disturbed. The exterior of the cocoon is very thin and if you are not careful, you could damage the pupa within. They are usually brown in color. Like the luna, finding them is easiest before the leaves drop to the ground, by looking for the contrasting color of the silk.
Callosamia promethea (The Promethea Moth): this common moth is very interesting, not only for its sexual dichromatism (males and females look completely different) but for the fact that males fly in the afternoon, as opposed to the night like most Saturniid moths. The cocoon is attached to the branch of the foodplant by a strong peduncle and usually incorporates a curled leaf, camouflaging itself almost perfectly. This is the easiest way to find them as they look exactly like a dead leaf that didn’t fall at the end of the season. It is common at times to find many of these hanging on a single tree. This also makes it easier for parasitic wasps to find them. The cocoon is very compact and features a valve at the top, allowing an exit point for the hatching moth the following spring.
Hyalophora cecropia (The Cecropia Moth): this is one of the most spectacular of the North American moths, not only because of its beautiful markings but because of its gigantic size! There are two variations to be found with the cocoons; one is loose and baggy and the other is tighter and more compact. They range in color from silver-gray to brown. They are attached lengthwise to a twig or branch and may incorporate leaves into its construction. Caterpillars will often leave the foodplant, preferring to spin up on a nearby bush, closer to the ground. The cocoon does feature a valve, used by the hatching moth to escape the confines of its winter prison.
If anyone would like to share photos of cocoons they have found, please post them in the comments below! The more images we have the better it will be for helping identify what they have found in the field!
As a final note on collecting cocoons, fellow Bug Guy Ryan Bridge recommends hunting with the sun behind you, as the casing of the cocoon reflects the sunlight. This makes them really pop. They are much easier to find this way. In fact I have found more cocoons in my area in the last two weeks than I have my entire life!