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Countershading and Caterpillars--Hickory Horned Devil, August 27-31

Sunday, October 2, 2022

I know it's been awhile since I posted a Hickory Horned Devil installment. Whoa it's been a busy fall! Thank goodness I took a few days to gather, edit, and upload all these photos so I could write the posts later. It takes forever to get them to load on my LTE-based Internet. Anyway, enough yangin'. I've got power and Internet, and that's a lot more than about a million Floridians have after that SOB Ian hit them.

This post covers a four-day span when the Devilworm was growing into its long silk stockings, getting more colorful by the day--even by the hour! 

27 August, 4:10 pm

Its face on 28 August. I love the little true legs clasped up under its chin like Dr. Evil!

The Alice in Wonderland comparison is apt. All this worm needs is a big amanita to sit on, and a hookah. Why didn't I arrange that?

People have been sending me newspaper clippings about people finding hickory horned devils. I love that. I think it reflects a growing awareness of caterpillars and just how cool they are. Would that have made the newspaper ten years ago? Doubting it. 

30 August--the dorsal zone is turning pale turquoise. This fifth instar is really a gas, with the psychedelic colors coming in. 
And here is where the Devil name comes from--the Ray-Bans on the dorsal surface of its thorax. The caterpillar has to be kind of annoyed to expose them. When it's feeling threatened, the caterpillar tucks its head against its underside, stretching the thorax to display the black "eyes." I love this look so much.

Just the best smile, don't you think? Or some say it's a Dali mustache. To me it looks like a devil with an orange crown, slightly askew. 

The caterpillar is so used to me I have a hard time getting it to expose the black spots I love to photograph. This is what the Ray-Ban's look like, closed up. I'm trying to get the bug to bow its head but nothing doing. Look how pale the dorsum, or back, of the animal is in this photo. Stay tuned for the reason.

Some mega-frass from the fifth instar devil. I open the sleeve and shake it to the ground daily to keep things clean in there. They look enough like grenades that I'm worried they'll blow up. The frass reflects the shape of the gut. That's a lot of absorptive surface!

Countershading is a fascinating natural phenomenon, and it is employed  by invertebrates and ungulates, fish and birds, to name a few. Check out the elegant countershading on these impala kids I photographed grooming each other in the Kruger of South Africa. Just where the belly starts to turn under and would be thrown into shadow in strong light, the local color of the animal lightens. And it goes to pure white on the underbelly. The net effect is that the animal's form loses its apparent shape and is flattened out, making the impala harder to see at a distance. They melt into the grass. 
This is called countershading, because the paler local color of the belly counteracts natural shadows. 

So when you've got a large, tasty caterpillar that habitually hangs upside down under twigs, the countershading is applied backward! With the HHD, its underside is darker than its dorsum, or top side. 
So it's hard to discern the creature as a rounded form--it dissolves into a patchwork of patterns, flattens out, and is really hard to see. The pale chevrons further break up its form. Perfect camouflage!

This is the sleeve. The caterpillar is about a third of the way down. Its camouflage is terrific. Sometimes I spent many minutes looking for it before I could see it. I knew it couldn't get out of the sleeve with the rope tightly wrapped at both ends, but I still sometimes concluded it had escaped before I finally saw it.

The pale chevrons on its flanks perfectly mimic the sun striking leaf edges, as you can see in this photo.
They and the countershading of the pale dorsum and dark underside make it simply disappear. Click on the photo to enlarge it for a better look--I'm going to bet you have a really hard time finding it in the small form.

And then there's the fascination of watching it demolish persimmon leaves. 

31 August,  7:22 pm . Enjoy your meal! 


Thanks for the views!

Awesome!!! Thanks.

I love seeing this caterpillar's progress. I hope it go on to breed many more marvels. Thank you for posting.

Gosh! I'm used to the little monarch and swallowtail frass. That's some big 'pillar poo!

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The camocoloration via countershading is amazeballs!

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