Feet first: How butterflies use their legs to taste the world

New Delhi: You must have seen butterflies on top of flowers and leaves, but have you ever wondered what they are up to? Or more specifically, have you wondered how they eat and taste? This might either disgust you or intrigue you to know more. Feet are the answer.

Butterflies get different tastes through their feet. Scientists say butterflies have taste sensors, called chemoreceptors, on their tarsi — the last segments of their legs.

When a butterfly lands on a leaf or flower, it drums its feet against the surface. That action releases plant juices and helps the insect “taste” whether the spot is good for feeding or egg-laying.

“If the plant has the right chemical signature, the proboscis uncoils and it starts feeding,” said Dr. Priya Menon, an entomologist at the University of Agricultural Sciences, Bengaluru. “If not, it moves on.”

The proboscis, a straw-like tongue, can only suck liquids. So the feet do the scouting.For female butterflies, this taste test is critical: they lay eggs only on host plants their caterpillars can eat. A wrong choice means the larvae starve.

Different species are wired for different plants. Monarchs taste milkweed. Lime butterflies check citrus leaves.