When it comes to ingenuity, the Golden Tortoise Beetle (Charidotella sexpunctata) larva has all others beat! Instead of discarding its feces, it collects them and uses them as a means of chemical protection. Golden Tortoise Beetle larvae have a “fecal fork” on their last abdominal segment which they hold over their body. They also possess a muscular, telescopic anus which they can manipulate in such a manner as to deposit their feces onto their fecal fork. Bits of shed exoskeleton combined with days of feces accumulate on this fork and create an effective fecal shield. Golden Tortoise Beetle feces contain alkaloids from the plants that they’ve eaten (Bindweed and other plants in the family Convolvulaceae) and consequently the shield wards off predators. (Photo: Golden Tortoise Beetle larva with fecal shield; inset – adult Golden Tortoise Beetle)
Instead of discarding feces, or frass, some insects save their waste matter for defensive purposes such as “fecal shields.” These are coverings over the back of the larvae that are made largely of feces and provide either physical or chemical barriers to predation. Adult Tortoise Beetles have a type of shield (hence, their name), but it is formed from expanded, hardened forewings, and is not a fecal shield. The larvae of these beetles have fecal shields which serve as chemical deterrents, preventing most predators from even touching them. The deterrent in the feces comes from the beetles’ food source — plants in the order Solanales. Tortoise Beetle larvae have what is known as a “fecal fork” on their last abdominal segment, which they hold over their body. The larvae maneuvers its muscular, telescopic anus, or “anal turret” in such a manner as to excrete its feces and bits of shed exoskeleton onto the fecal fork, forming an umbrella-like fecal shield.
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