398 TRANSFORMATIONS OF INSECTS. 
tube, which is pierced at its extremity by two orifices, which are 
surrounded by a crown of small hairs. The larva chooses shallow 
waters to swim about in, and when it requires air and a supply 
THE METAMORPHOSES OF Stratiomys chameleo. 
of breath, it sticks up the end of its body and elongates the last 
segments, and respires through the two holes just mentioned. 
After a longer or shorter larva life, the insect comes up to the 
surface of the water and floats; it does not change its shape, but 
