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.