Metamorphosis completely restructures a caterpillar's wormlike body and, you would think, its brain. But caterpillars may not be so wasteful. New research shows that some of their brain cells remain intact through the supposedly annihilative process.
Scientists have long been interested in whether butterflies can remember experiences they had as caterpillars, but teasing memory from the simpler concept of familiarity is difficult, says Martha Weiss of Georgetown University in Washington, D.C.
Now Weiss and her colleagues Douglas Blackiston and Elena Casey have found a way. The team put tobacco hornworm caterpillars (Manduca sexta) in the stalk of a Y-shaped tube with one arm that contained a smelly, ephemeral gas. The researchers gave the caterpillars a mild electric shock when they went down the arm with the gas. Some of the caterpillars had undergone their third molt and others had completed their fifth and final molt.