Happy Friday bug fans! Once again it’s time for another edition of Friday Flyers. And also this week, we hope you’ll have a wonderful Thanksgiving!! If you’re like us, you may overindulge and even put on a few pounds with all the second helpings...especially the desserts. Maybe next week you’ll even feel like it’s time to try and walk those extra pounds off. If you’re a nature lover, we may have a solution for you. It’s just about the right time of year to start going on nature walks to look for cocoons!!! So this week we thought we’d give you a few pointers on how to get started.
In order to be successful in looking for, AND ACTUALLY FINDING, cocoons, you need a little luck, and a little effort, but mostly some basic knowledge. The reason it’s a good time to start looking is because most of the leaves have fallen off of the trees, and it’s not too cold yet. Also, most winter predators like birds and squirrels have not found them yet. So, where do you start? The first thing you need to know is what you’re looking for. The types of cocoons you’re most likely to find are those of the large Saturniid moths. In our area these would be Cecropia, Promethea, Polyphemus, and Luna moth cocoons. These are the largest, most visible, and therefore, the most likely to find. We have pictured these 4 moths and their cocoons in our album. Obviously, you don’t need to know what the moths look like in order to find their cocoons, but knowing the species might give you the extra incentive you need on a cold day outdoors.
The second thing you need to know is what kinds of plants do their caterpillars eat? The caterpillars usually make their cocoons on their food plant. All of these caterpillars eat a variety of plants, but we’ll tell you what we usually have seen in our area. The easiest one to find is the Promethea cocoon, so in this edition of Friday Flyers, we’ll only discuss the Promethea Moth in detail. They eat wild cherry and lilac in our area, but we have only found them on the cherry trees, most often on the younger trees, usually about 5 to 10 feet off of the ground. Their cocoons look like the last remaining dead leaves hanging on the branches. They blow in the wind like leaves, but they hang “heavier”. Sometimes you’ll find several on the same tree, because the adult females lay clusters of eggs on the leaves and the caterpillars stay together when they are young. Promethea caterpillars make their cocoons from a light tan colored silk that they produce from a gland in their mouths. In the Fall, they crawl to a large green leaf and secure it to the branch with silk so that it won’t fall off even in a strong wind. Then they enclose themselves inside it by curling the leaf edges around them into a sort of tube, and fastening the leaf edges with their silk. Then they proceed to completely enclose themselves inside a silk “capsule” in which they will remain dormant until the Spring. We have watched this procedure thousands of times. It usually takes 36 to 48 hours. The cocoons always look the same except for some slight size differences, usually the females are larger. When the leaves fall off of the trees, the cocoons are still hanging there, sometimes with a few other empty leaves just to fool their predators. In the old days of cheap gasoline, we used to drive slowly down the country roads and spot them from the warmth of the car. But that’s not too cost efficient now, and if you’re trying to lose those extra Thanksgiving pounds, it won’t happen if you’re sitting in your car! About half of the cocoons you’ll find will already be hatched, because they are from the previous generation. The silk, although totally biodegradable, is strong enough to last a year in the wild. You can tell which cocoons have hatched because they are lighter weight, and there is a visible hole in the bottom where the moth emerged.
The final thing you might be wondering is, why do you want to find cocoons in the first place? The best reason is because these large moths are fascinating. The adults emerge in totally pristine condition with their colors the most vibrant. For those of you who might want to raise them, Saturniid moths are the easiest and largest of any butterfly or moth in our area. They make great photographic subjects in all stages of life, and the transformation that occurs inside the cocoon is one of the true wonders of nature.
This is the simplified explanation of how to find cocoons successfully. The method is similar for the other moth species we mentioned, except the food plants are usually different. For Cecropia moths, the preferred tree in our area is Maple, followed by Birch and several others. For Polyphemus moths the preferred tree is Oak. And for Luna moths, the preferred trees are Hickory and Walnut. The cocoons all look different, but when you get a little experience, you’ll be able to spot them fairly easily. These moths are all fairly common, but probably less than one percent of the trees will have cocoons on them, because most of the caterpillars don’t live long enough to make their cocoons due to predation. And don’t be discouraged if you don’t find any cocoons on your first attempt. Remember, they’ve had hundreds of millions of years to evolve their camouflage strategy. That’s why it’s so rewarding when you find them. See you on the trail!!! (And don’t forget to leave some for us.)
We hope you enjoyed this week’s edition of Friday Flyers. We love sharing our interest in butterflies and insects with you. Please enjoy the photos we have posted with this week’s edition, and be sure to see all the previous pictures in our Friday Flyers album. Remember to “like” our Wonders Of Nature page, and be sure to pass it along to all your Facebook Friends. We hope you’ll visit our Wonders Of Nature department soon, and we look forward to seeing you.
A beautiful male Cecropia moth!
This is a Cecropia moth cocoon. They can be wide like this, or more airy, but these are the largest cocoons in the USA, and rather easy to find. They measure around 4" across, and are often on Maple or Dogwood.
A gorgeous Luna moth! This is probably the most well-recognized moth in our area. It's the one they use in the Lunesta commercials!
A Luna moth cocoon, the hardest one to find!
A beautiful Polyphemus moth! These can vary from tan to reddish brown, but the big blue eye spots on their bottom wings make them easy to identify. They are big - often reaching over 5" across!!
A Polyphemus cocoon. Normally they are low down and often in leaf litter around Oak trees or Dogwood. Because of this, they are often found by scavenging squirrels and raccoons. In our area this moth is becoming scarce due to all the burning of the wild areas at the forest preserves.
A female Promethea moth! This is one of the more common giant silk moths found in northern Illinois, and it is one of very few species in which the male and females are different looking.
A male Promethea moth, freshly emerged from his winter cocoon! The males fly at dusk, around 5:30pm to 6:30pm. They are big - over 4" across!
A Promethea cocoon - the most classic cocoon shape. You'll see these hanging from branches in the winter.