We received an interesting, if somewhat vague, question from a reader about a brown worm he found in the garden. The worm was described as not only “brown,” but also “fat.” The fat, brown worm is about two inches (five centimeters) long, and its body dimensions resemble that of the “tomato hook worm,” by which we are fairly sure our reader meant “tomato hornworm,” the larval form of a moth (Manduca sexta), making the tomato hornworm a caterpillar. Speaking of caterpillars, it is possible our reader found a fat, brown caterpillar, as opposed to a fat, brown worm, so that is something to keep in mind as we consider some possibilities for what our reader might have found in this garden.