Over five years ago I wrote about a remarkable adaptation in insects: mimicry of snakes. Remember that “holometabolous” insects go through very different life stages, and this includes Lepidoptera, which have larvae that become pupae (also known as “chrysalises”), and out of those pupae hatch the winged adults. The larvae (“caterpillars”) are often highly edible to birds and other predators, and have to evolve various strategies to avoid being eaten. Snake mimicry is one such strategy.
In 2020 I described one example of a caterpillar mimicking a snake. When the caterpillar is disturbed, it displays a remarkably snakelike underside and rears its head like a venomous snake. This is the Snake-mimic caterpillar, Hemeroplanes triptolemus, a moth from the Amazon rainforest found in Puyo, Ecuador. The video was taken by the late Andreas Kay, who rediscovered my frog Atelopus coynei. (Kay’s photos are now curated by reader Lou Jost.) I’ve put Kay’s video below again—it’s the second one in this post.
But pupae, being immobile (well, as you’ll see, they can sometimes move a little), have a bigger problem, for they don’t have much behavior to deter predators. In another post from 2015 I described and showed some photos of a pupa that, like the caterpillar above, also resembles a snake. (It’s a different species from the one above; the pupal mimic becomes a butterfly while the larval mimic turns into a moth.) I also noted that the pupa could actually move a bit, and it’s likely that even a little motion might deter a predator. But at that time I had no video to show.
Recently I found that in fact Kay did take some video of the snake-mimic pupa and had put it up in 2018. Ergo, just below, in the top video, you can see a pupa that resembles a snake. The resemblance of both moth and butterfly mimics is so close to that of a snake, both morphologically and behaviorally, that it’s hard to think of any explanation other than Batesian mimicry.
First, here are Andreas’s YouTube notes:
This chrysalis or pupa of the Daring Owl-Butterfly, Dynastor darius, was filmed in the Jardin Eco-botanico Mindo, Ecuador. It mimics the head of a snake which gives it an advantage in the struggle for survival by scaring off predators such as birds. It has fake eyes, a fake mouth, fake scales and even strikes like a snake if disturbed, as shown in this video.
And look at it move! How does the immobile and developing butterfly adult know that something’s threatening it? It appears to have a sense of touch.
And here again is the moth larva mimicking a snake; a video I showed before. You might want to ponder the incipient stages of this adaptation—what were the first snake-resembling features to evolve?