112 



METAMORPHOSES OF INSECTS. 



Fro. 333. GNAT AND LARVA. 



which render themselves so unpleasant to Man by their venomous 

 punctures, live in the water during their larva state. They 

 are then vermiform, destitute of limbs, and have the abdomen 



terminated by bris- 

 tles and some appen- 

 dages arranged in a 

 radiated form (Fig. 

 333); and from their 

 last ring arises a long 

 tube, by the aid of 

 which the animal 

 draws in from the 

 atmosphere the air 

 which it requires. 

 To breathe by this 

 means, it suspends 

 itself as it were from 

 the surface of the 



water, with its head downwards ; and we see it performing this 

 movement at short intervals. The Chrysalis continues to live in 

 the water, and to move about there ; but instead of breathing 

 like the larvse, it draws in the air which it requires by means of 

 two pipes, placed upon the thorax. It floats on the surface of the 

 liquid ; and after having completed its metamorphosis, the per- 

 fect insect uses the skin of the chrysalis as a boat, until its long 

 legs and wings have gained sufficient strength to enable it to 

 move on the surface of the water, or to fly away ; but if its 

 body happens to be submerged, as often occurs when the wind 

 upsets these frail barks, it is infallibly drowned. 



632. The Insects with incomplete metamorphosis also pass 

 through the larva and chrysalis state, before arriving at the 

 perfect state; but here the larva only differs from the perfect 

 insect by the absence of wings ; and the state of the chrysalis is 

 only characterised by the gradual development of the wings, 

 which, at first folded back and concealed under the skin, then 

 become free; but only acquire their full development at the 

 period of the last change. We may mention, as examples of 



