Animals
Do butterflies taste with their feet?
The short answer
Yes. Butterflies have chemical sensors on their feet, so when one lands on a leaf or a flower it is tasting it. Females use this to check a plant is the right kind before laying eggs on it, since most caterpillars can only eat a few specific plants.
A butterfly's tongue is a long coiled straw, good for drinking nectar but useless for inspecting a leaf. So the inspection happens at the other end. The feet carry taste receptors, and when a butterfly drums them against a surface, as they often do on landing, it is sampling the plant's chemistry.
The proof dates to 1922, when researcher Dwight Minnich touched butterflies' feet with sugar water and watched them unroll their tongues in response, the same reflex you would get by putting sugar on a human tongue. The feet had tasted it.
For a female butterfly this is a matter of life and death, though not her own. Her caterpillars will hatch on whatever leaf she chooses, and many species can digest only one or two kinds of plant. A monarch that laid on the wrong leaf would lose the whole brood. So she lands, drums, tastes, and moves on until the foot says yes.
Sources
- Dr. Universe explains how butterflies taste with their feetWashington State University
- Do butterflies really taste through their feet?Carleton University Department of Biology