INSECTS 



81 



FIG. 136. Measuring worm, 

 the larva of a moth. 



stages : (i) egg, (2) larva> (3) pupa, and (4) imaga, or per- 

 fect insect (Figs. 136, 137, 138). 



The egg stage is one of development, no nourishment 

 being absorbed. The larval stage is one of voracious feed- 

 ing and rapid growth. In the pupa 

 stage no food is taken and there is 

 no growth in size, but rapid devel- 

 opment takes place. In the per- 

 fect stage food is eaten, but no 

 growth in size takes place. In this 

 stage the eggs are produced. When 



there is very little resemblance between 

 the larva and imago, and no pupal stage, 

 the metamorphosis, or change, is said to be 

 complete. When, as with the grasshopper, 

 no very marked change takes place between 

 the larva and imago, there being no pupal 

 stage, the metamorphosis is said to be in- 

 complete. By studying the illustrations and 

 specimens, and by thinking of your past observations of 

 insects, determine which of the insects in the following list 

 have a complete metamorphosis : beetle, house fly, grass- 

 hopper, butterfly, cricket, wasp. 



FIG. 137. Pupa 



of a mosquito. 



FIG. 138. THE FOUR STAGES OF A BOTFLY, all enlarged. 



a, egg on hair of horse (bitten off and swallowed) ; b, larva; c, larva with hooks for holding 

 to lining of stomach; d, pupal stage, passed in the earth; e, adult horse fly. 



G 



