DEVELOPMENT AND METAMORPHOSIS. 



41 



increase in size, the wing pads develop into wings, the 

 adult colorings of black and red appear until, when adult 

 size is reached, we see a familiar box elder bug with its 

 red "X" on its black back, its gauzy under wings for 

 flying, and its slender legs to carry it elBciently about 

 into more places than we wish it could get into. 



Fig. 20 — Six successive instars of the squash bug, Anasa tristis. X 2. {Polsom.) 



In this form of metamorphosis there seem to be but 

 two intermediate stages, the egg and the larval stage, the 

 latter greatly extended. (Fig. 20.) Where the insect has 

 complete metamorphosis, the food habits of the adult 

 generally differ from those of the larva; but where the in- 

 sect comes to adult form by incomplete metamorphosis, 

 the young usually has the same food preferences as it will 

 have later in life and as its parents had before it. 



