Proboscis is a structure that is mostly found in insects. A proboscis is a tubular mouthpart that is used for feeding, sucking up liquids, or probing. It is a long, thin, and flexible appendage that is located on the head of the insect. Some insects, such as butterflies, moths, and mosquitoes, have a proboscis that they use to extract nectar from flowers or blood from animals. Other insects, such as flies, use their proboscis to feed on decaying matter or to lay eggs. In contrast, tapeworms, amphibians, and mollusks do not have a proboscis.