Brightly Colored Caterpillars in the Woods

Just a couple of days ago we received a laconic email from a reader. He sent us a photo of what appears to be a caterpillar with one simple question: “Can you tell me what this is[?]” The caterpillar – if it is a caterpillar (and it probably is) – appears to be a bright color. It is perhaps yellow or maybe even entirely white. (The photo of the caterpillar is a bit hard to decipher, as you’ll soon see.) It also appears to be in the woods, or at least some natural setting with rocks, dirt, twigs, and similar such things. So, we have a seemingly simple question before us: what is the bright colored caterpillar in the woods?

We say this is a “seemingly” simple question because in fact it is actually not that simple. The reader may only be asking one thing, but what he is asking is quite difficult: to identify a caterpillar with the help of only one unclear picture. The reader didn’t supply any additional information, like where he found it (in terms of geography), so the picture is all we have. Identifying caterpillars is always hard because there are tens of thousands of species, and it is especially hard when we possess incomplete information. However, we do have the picture, so we’ll do with it what we can. Here it is:

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Bright Caterpillar

As you can see, the photo is overexposed, making it difficult to decipher exactly what you are looking at initially. Indeed, it is not even immediately clear what the creature in question is – a couple of things look like they might be alive. However, we are pretty sure the reader is wondering about the creature in the middle, the one that is white (but may in fact be another light color washed out in the photo) and appears to have a segmented body. So, what kind of caterpillar is this?

The only possibility that comes to mind is some species of swallowtail caterpillar – that is, the larval form of a swallowtail butterfly – which we say for a couple of reasons. One, these caterpillars are common and are found all over the globe, so regardless of where our reader is located, he might have found one. Two, many swallowtail caterpillars have large heads – see this pictures in our article about the Eastern Tiger Swallowtail Caterpillar, for instance – and it appears that the caterpillar in the picture has a large head. However, we aren’t particularly confident in this suggestion. It’s a possibility, but not one we’d wager much on. (There are also 550 species of swallowtail caterpillars, so even if we’re correct, there is still some narrowing down to do.)

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Unfortunately, we can’t answer our reader’s question with anything resembling certainty. We have too little information, and the picture isn’t clear enough to offer a well-informed suggestion to our reader. We encourage him to look into swallowtail caterpillars, however, as he’ll probably at least be able to recognize a match of what he saw.

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