Tuesday, August 4, 2015

Imperial Moth

This past Saturday Joe Letsche, the naturalist for the Ross County Park District, held an arthropod night at the Buzzard's Roost Nature Preserve. It was a great gathering of insect-and-arachnid-loving people, with an amazing array of arthropods to boot. There will be several future posts going over some of the goodies from that night, but I want to start with this. In keeping with this year's apparent "really big and awesome moths" theme (see my previous posts on the Cecropia Moth and the Luna Moth), here's the Imperial Moth!

Imperial Moth
This beautiful moth is the Imperial Moth, Eacles imperialis. This species, the Cecropia Moth, and the Luna Moth all belong to the family Saturniidae; however, the Cecropia and Luna belong to the subfamily Saturniinae, better known as the Giant Silk Moths. The Imperial Moth, on the other hand, belongs to the subfamily Ceratocampinae, better known as the Royal Moths. This species ranges throughout the entirety of Ohio, with records from nearly all the counties. It is worth pointing out that although it ranges across Ohio, the Imperial Moth seems focused on the southern and eastern parts of Ohio. It can be found in deciduous, coniferous, and mixed forests. The Imperial Moth's habitat gives us a clue to understanding their strange coloration. Moths are heavily preyed upon by a variety of predators, and as a result most moths have developed some sort of visual defense mechanism. Some use camouflage and look like lichen found on trees or other natural objects. Others mimic wasps, toxic beetles, or even hummingbirds in the case of the Hummingbird Clearwing. How does the Imperial Moth avoid predation? Well, it looks like a dead leaf! During the day this moth sits on the forest floor, pretending to be a leaf until nightfall. If you passed this moth while it happened to be on a pile of yellow and brown leaves (which are especially abundant this time of year), you would never notice it!

Imperial Moth
The Imperial Moth has another thing going for it when it comes to camouflage: variation. There is a huge amount of pattern variation in this species; simply compare this individual with the previous individual pictured above to get an idea! Okay, so imagine you were told to find some camouflaged objects in the forest, and let's say all these objects look exactly the same. It will be hard to find the first few, but eventually you'll begin learning what to look for. Soon you'll start getting faster and faster as your brain recognizes the same patterns over and over. Good for you if you're a predator, bad for you if you're the prey. Now, imagine you are told to find another set of camouflaged objects, but this time all the objects vary slightly in pattern and coloration. You never really develop "eyes" for that object, and you struggle to find it. This time it's bad for the predator, good for the prey. This is exactly how the Imperial Moth excels. Overall, they all look like a dead leaf, but they all look like different dead leaves, just like how all dead leaves vary. Birds and other predators have a very hard time learning to pick them out of all the background noise, resulting in more Imperial Moths surviving to reproduce and passing on their color variations.

Imperial Moth Size
The Imperial Moth is a very impressive moth to see in person. There's variation in wingspan sizes, but they typically reach 3-7 inches. Females, such as the one above, are typically larger than males. The Imperial Moth does come to lights, and we had 3 individuals visit the mothing sheets over the course of the night. In Ohio, these moths begin flying in late June through mid-August.

Imperial Moth
When it comes to these large moths, I really like to try and get a shot of their face. There's something adorable, in my opinion, about these ridiculously-furry moth faces, although I know many probably disagree.

As I said before, I have several posts coming up from this night, so stay tuned! Thanks for reading!

4 comments:

  1. Beautiful close-up of the face! Thanks for explaining that they rest on the forest floor and therefore blend in with the leaves. I also did not know that they are so variable.

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    1. Thank you Lisa! And thanks for reading!

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  2. Love your blog. We were just at McCormick's Creek State Park in Indiana to hike and saw one on the door to the Canyon Inn. I was able to tell my daughter about your recent post. Thanks for educating us!

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