Butterflies Taste With Their Feet
Yes, we really mean that. Butterflies have receptors on their legs that are similar to those in the taste buds of the human mouth, only 200 times stronger [source: Encyclopedia Britannica, Clare]. In butterflies, these receptors are used primarily to test potential egg-laying sites for toxins or other detriments that could harm their offspring [source: Encyclopedia Britannica].
Full-grown butterflies don't eat -- they only drink -- but their caterpillars eat constantly [source: San Diego Zoo]. Once the eggs hatch, they start feeding on the leaves under which they were born. Since some plants produce toxins as a defense mechanism, choosing the wrong leaves can prove catastrophic [sources: San Diego Zoo, UC Irvine]. That's where mommy's feet come in.
When a female butterfly lands on a leaf, she tastes it to determine whether it's safe for her babies. If her feet detect nothing awry, she knows she can safely raise her caterpillars there.