Re: how do locusts breathe

Hi Tanya-

A very good question! Locusts, like most insects, have what entomologists refer to as a ventilatory system. Instead of using a circulatory system and hemoglobin like you and me, most insects directly vent every cell with the outside environment and exchange oxygen directly.

Along an insects' side, there are small holes called spiracles; these are the openings to the ventilatory system and there are usually two per segment: one on each side. The spiracles often have some sort of valve, that allows the insect to close off its ventilatory system- this is analagous to holding your breath. I've seen some insects stay lively in a jar full of ethyl acetate (the gas I use to knock them out) for an hour or longer!

Inside of the the spiracles are the trachea, which branch out into smaller tracheoles (which you might notice is the same as the names of similar structures found in the vertebrate lung). The smaller tracheoles are where gas exchange occurs with the ventilated cells- particularly where there is a large oxygen requirement. Flight muscles (which are very large in the locust) are generally highly tracheated so lots of oxygen can get in to the muscle cells when they're flying. Below, I've included a diagram of a cross section through and insect, showing the location of the trachea and tracheoles:

You might also be interested in a brief introduction to insects at the Urban Entomology site here , or the BugBios site is always a great resource on things entomological. My personal favorite entomology text is the third edition of "The Science of Entomology" by William S. Romoser and John G. Stoffolano, Jr. (publisher: Wm. C. Brown, Dubuque, Iowa), which has goes into depth on most important aspects of insect physiology, including a really good section on the ventilatory system.

Rob Campbell, MAD Scientist