How do Monarch butterflies breathe?
When we breathe, oxygen goes into our lungs and is picked up by blood which carries it to cells throughout our body. Because we are relatively large, we need this complicated system. But insects are so small that tiny air tubes (called tracheae) carry air from the outside directly to body tissues. Air enters and leaves these tubes through small holes (called spiracles) on the outside of the thorax and abdomen. Spiracles are easily seen on larvae and pupae but are difficult to see on adults because they are obscured by scales.
