Gases cannot exchange through the exoskeleton of insects because it's hard and waxy.
Insects have small pores along their bodies called spiracles.
A tube called a trachea comes from the spiracle and branches out into tracheoles that contain a fluid which delivers oxygen to the cells in the insect.
The trachea of insects is supported by rings of chitin to keep them open.
Tracheoles run between cells into muscle fibres where gas exchange occurs.
Very active flying insects need lots of oxygen.
Flying insects close the spiracle using abdominal muscles to create a pumping movement for ventilation.
During flight, the fluid is drawn into the respiring muscles of insects.
