The only American butterfly known to have become extinct from human cause is the Xerces blue, which vanished from the San Francisco Peninsula in 1943. Butterflies are ideal monitors for habitat destruction, pollution and the overuse of pesticides and herbicides. Also, since nectar is the food of most adult butterflies, as they visit flowers they transfer pollen, assisting in crop pollination. They are also an important part of the food web. The antennae of most moths are tapered at the tip and are feathery.
Most butterflies are active in the day.
Most moths are active at night. Butterflies, at rest, hold their wings vertically over their back. Moths fold their wings over their back or extend them to the sides. A butterfly's wings are not hooked together. Moth's wings are often hooked together.