Mid-Week Mini: Butterflies Taste with their Feet

In this week’s Mid-Week Mini Episode, we talk how butterflies taste with their feet.

Imagine sitting down at a restaurant, looking over the menu, ordering a cheeseburger, and then when it arrives, instead of taking a bite, you just take off your shoe and step directly into it. And then you go, “Yep. That’s a cheeseburger.” Because if you were a butterfly, that would make perfect sense.

Butterflies taste with their feet.

Now, they don’t ONLY taste with their feet. Butterflies have chemical receptors on other parts of their bodies, including their antennae and proboscis — that long, straw-like mouthpart they use to drink nectar. But a huge part of their sense of taste comes from receptors located on their feet.

And there’s a really good reason for this. A butterfly doesn’t have hands, so when it lands on something, its feet are one of the first parts of its body to make contact. Those feet contain sensory receptors that can detect chemicals in whatever surface the butterfly is standing on. In other words, landing on something gives the butterfly information about what that something actually is.

This is especially important for female butterflies, because they have to decide where to lay their eggs. Caterpillars can be incredibly picky eaters, and many species are adapted to eat only particular kinds of plants. A monarch caterpillar, for example, depends on milkweed, so putting an egg on the wrong plant could mean that when the caterpillar hatches, there’s nothing there it can eat.

So the female butterfly lands on a potential host plant and essentially samples it. In some butterflies, you can actually see the female tapping or “drumming” the surface of the leaf with her legs. That behavior helps expose her sensory receptors to chemicals in the plant, allowing her to determine whether she has found the right place to leave her eggs.

And this isn’t just something scientists inferred because butterflies seemed unusually interested in stepping on their food. Experiments have shown that butterflies can distinguish between substances such as sugar solutions, salt solutions and other chemicals through contact with their feet alone. Researchers identified specialized chemical-sensing structures in the tarsi — basically, the end sections of the legs.

Which means a butterfly landing on you might be a little less adorable.

Because yes, when a butterfly lands on your hand or your arm, some of those taste receptors are coming into contact with your skin. The Florida Museum of Natural History points out that butterflies landing on visitors in their Butterfly Rainforest can probably taste them.

So the next time a butterfly lands on you and somebody says, “Awww, it likes you,” you can ruin the moment by saying, “Actually, it’s licking me with its feet.”

And that sounds completely made up, but the Internet Says it’s True.