Worm that looks like snake

Orange Dog Caterpillar (Papilio cresphontes)

A while ago, a reader requested that we identify a caterpillar that looks like a snake. As is sometimes the case with caterpillars, we struggled to identify the exact species our reader found. (There are tens of thousands of different caterpillar species, after all.) Fortunately, we received a couple of comments on this post, and one of them put forward a plausible hypothesis: the caterpillar that looks like a snake may be an Orange Dog Caterpillar, or Orangedog Caterpillar, if one has a Germanic tendency to combine words into a single compound. (One might also just refer to it by its scientific name: Papilio cresphontes.) The commenter pointed out that the Orange Dog Caterpillar actually looks more like bird poop than a snake; in fact, Orange Dog Caterpillars are often called “bird-poop caterpillars,” evidently. (Snakes are presumably offended by the competing descriptions.) In any case, we’ve compiled some information about the Orange Dog Caterpillar below, as well as included the picture of the creature that has likely now been positively identified.

Here is the photo the reader originally submitted with his question:

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The picture isn’t totally clear, but you can see how it might be simultaneously described as bird poop and a snake. Its coloring is a mixture of grey, black, and white, and on a branch it might look like a glob of, well, you get the idea. On the other hand, the creature appears to have two eyes on the end of its body, just like a snake. These “eyes” are as good a starting point as any for our discussion of Orange Dog Caterpillars.

These caterpillar eyes are not, as our use of quotes in the previous sentence suggests, eyes at all. Rather, they are eyespots, which serve as a defense mechanism. Among other things, eyespots can make an animal (e.g., a caterpillar) look like a different animal (e.g., a snake), thereby deterring predators from attacking them. Various animals have eyespots, including numerous species of caterpillars. Indeed, eyespots are commonly on the caterpillars that belong to the Papilio genus, of which Orange Dog Caterpillars (a.k.a. Papilio cresphontes) are obviously an example. This topic – members of the Papilio genus having eyespots – has actually come up multiple times, such as when we wrote about Tiger Swallowtail Caterpillars.

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Although people see Orange Dog Caterpillars from time to time (clearly, given our reader’s question and our commenter’s remarks), the adults they become – Orange Dog Butterflies – are probably better know. They are commonly found in North America and a few parts of South America, often in deciduous forests. They are also found in citrus orchards, where they are regarded as a pest because of the damage they cause to crops. The adults are very large, with wingspans of about 4-6 inches (10-15 centimeters), and in fact are the largest butterflies in the United States and Canada.

We aren’t absolutely certain that our reader found an Orange Dog Caterpillar, but this seems likely. The picture above, even though it isn’t perfectly clear, appears to show an Orange Dog Caterpillar, and this species of caterpillar is common too. We thank our reader again for his question and picture, and we very much appreciate the comment that helped us identify the caterpillar we were struggling to name.

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