“What is this?” is all this reader writes to us about the brown caterpillar in this excellent photograph below. At the tip of this cute creature sits its voluptuous head, adorned with pink, triangular markings, as well as some cartoon-like, yellow eyespots.

Some time ago, a reader asked us to identify a brown “worm” he found. The creature was brown with a big head, on which there appeared to be two eyes. We placed the word “worm” in quotation marks because the reader did not in fact find a worm, but rather a caterpillar. Of this much we were fairly certain when we first attempted to answer our reader’s question. However, we were unsure exactly what the brown caterpillar was, as in, what precise species of caterpillar our reader came across. Thanks to reader comments, we are now confident that our reader found an Eastern Tiger Swallowtail Caterpillar (Papilio glaucus).