What's Buggin' Ya?
One of the biggest clues in deciphering the identity of Buffalo Bill is also the smallest one: a bug cocoon found inside a corpse's throat and extracted in an extremely disturbing scene. Clarice takes the cocoon to a museum, where it is identified as Acherontia sty, the Death's Head Moth from Asia. One of the scientists observes, "Somebody grew this guy, fed him honey and nightshade, kept him warm. Somebody loved him." Who knew Buffalo Bill was capable of love, even if it is just for an insect?
Hannibal Lecter analyzes the significance of the insect just as we would, saying, "The significance of the moth is change. Caterpillar into chrysalis, or pupa, from thence into beauty. Our Billy wants to change, too." But the death's-head moth isn't beautiful. It's creepy, making it the perfect pet for the even-more-creepy killer.
Because of the rarity of the moth, the FBI is able to find customs papers leading them to Buffalo Bill. They lead them to the wrong house, but still… When Clarice ends up at the right house, it's the rare moth flitting around that confirms her suspicion that the man is Buffalo Bill. If serial killers didn't have such odd quirks, like killing people according to seven deadly sins or keeping strange moths, maybe they'd get away with it.
Mad About the Moth
The moth is an iconic symbol from Silence of the Lambs. It's featured on the poster and was parodied in Mad Magazine's "The Violence of the Hams" as a moth with Roseanne's head.
The actual moth survives by sneaking in bee hives for an all-you-can-eat honey buffet. Scientists believe the mark on its back isn't a skull, but a mark to disguise it as a bee. Funny enough, this analogy still works as a symbol for Silence, as Buffalo Bill wants to disguise himself as something else.