Butterflies taste food by standing on it with their feet.

Butterflies have sensors called chemoreceptors on their feet. These sensors are much more sensitive than a human tongue. When a butterfly lands, it drums its feet to release juices from the plant. The sensors tell the butterfly if the plant is safe or poisonous.Most caterpillars are picky eaters and can only survive on specific plants. For example, Monarch butterflies only lay eggs on milkweed. Their feet look for a specific chemical called cardenolides found in that plant. If they do not find the right chemical, they fly away to keep searching.This process is called oviposition drumming. It saves the butterfly from wasting eggs on a plant where the babies would starve. While butterflies have a straw-like mouth called a proboscis for drinking nectar, it does not have these same taste sensors.Scientists have found specific genes that build these foot sensors. These genes evolved over millions of years to match the plants the butterflies live near. This creates a lock and key system between the insect and the leaf. It is one of the most precise ways any animal finds food.