Butterflies and Moths, like humans, produce energy to live by burning up the food they take in with the oxygen in the air they breathe. Humans breathe through their noses and mouths, but insects take in air through tiny holes called spiracles along the sides of their thorax and abdomen.

On the larva of the Puss Moth, the spiracles lie in a row of white spots along the side of the abdomen.

On the pupa of the Elephant Hawk-moth, the spiracles are easily visible along the sides. On the right is a close-up of the end of the abdomen.

Here is a close-up of the breathing pore or spiracle of a larva of the Privet Hawk-moth.The vertical slit in the middle can be opened and closed.