What is the primary mode of feeding for adult butterflies and moths?

The primary mode of feeding for adult butterflies and moths is siphoning, which is facilitated through their specialized mouthparts known as proboscises. This long, tubular structure allows them to reach nectar deep within flowers, where they extract the liquid using a sucking motion. The siphoning method is particularly effective for accessing the sugary fluids in flowers, which are essential for their energy needs.

In contrast, other feeding methods are not applicable to adult butterflies and moths. Chewing is characteristic of insects such as beetles, where the mouthparts are designed to crush and grind food. Sponging is associated with certain types of flies and involves absorbing liquid through spongy mouthparts. Piercing is seen in insects like mosquitoes, where long, needle-like mouthparts are used to pierce skin and draw blood. Therefore, siphoning is uniquely adapted for the feeding habits of adult butterflies and moths, making it the correct answer.