The head of an insect has two beards, which are called antennae, just like "antennae". They have different shapes and are very strange.

Antenna has other functions besides smell, touch and feeling. Its function is equivalent to human nose, fingertips and ears. There are also many sensory organs with different shapes on the antenna, which can be used to receive and distinguish smells. Butterflies that harm citrus reticulata can accurately land on orange trees and potato ladybugs can accurately land on potato leaves to lay eggs, all of which rely on antennae to distinguish smells. In addition, crickets can "hear" sounds by the shin tendons of their forelimbs, and cicadas can "hear" sounds by the sensory organs under the tympanic membrane of their abdomen.