This morning I had a look around my yard after being away for the past week, and I met this fantastic creature on a leaf of one of our cultivated hazelnuts:
Its body was awkwardly contorted, and it took me a lot of tries to get a photo with all (or most) of it in focus.
When it started walking around, I was surprised to see that it was able to unfurl those tendril-like appendages (even harder to get in focus when it was in motion, but these photos will give you some idea).
This strange beast is a horned spanworm (Geometridae: Nematocampa resistaria), something I’ve encountered only a couple of times before, and this one was the largest and fanciest. Here’s a very young one I found on a black cherry leaf on 6/13/2013:
And one found on a woodland sunflower, 6/8/2019:
Although today’s larva was the first I’d seen in my yard, I spotted an adult of this species on the basement ceiling on 7/6/2014:
The caterpillar seems like something that belongs in the tropics, and sure enough, here’s a video showing a Nematocampa larva in action in a Peruvian rainforest:
BugTracks 
Hi Charley, What is your ID for this gall I encountered? https://www.inaturalist.org/observations/81601477
Wow, Charley, I had a parallel experience here in Marlboro, VT yesterday afternoon. Photographed this tiny curiosity inching its way across our picnic table (under a large oak) while I was taking a garden break in the shade. Most grateful for your ID, photos, and added info!
What an amazing series of photos of a most interesting creature! Thanks for sharing!
This is such fun! Thanks for all the info you give us on the tiny, unappreciated bugs that populate out world:>). I was going to add a picture of a caterpillar on a coneflower that had attached pieces of the flower to its body, but no way to do that.
Stay cool, and keep posting:>)
That would be this one! I don’t think I’ve ever found a larva of that species, though.
100% – thanks:>). If you want one of my images, let me know. Otherwise, no need to respond. I captured it July 25th, 2020. We do have the moth here, I’ve just never seen the larva before – too good at camouflage:>)
Love it! Never would’ve guessed that it could have control of the “tentacles” like that. Thanks for this!
Your photos are amazing. When I first saw them in a small verison on notifications, I thought they were photos of ginger. Then at times they look like seahorses or half-plant, half-insect.
If this thing is tropical, will it do damage here?
It’s a native species, it just has a relative in the tropics.