INSECTS. 



217 



facts of life-history. In the first or ametabolous group the 

 young leaves the egg with much the general shape of the 

 adult, and the growth is gradual, without any sharply marked 

 lines between the different stages. Such is the case with 

 the grasshopper and the bug. In the other or metabolous 

 group we can distinguish three stages sharply marked off 



FIG. 95. Colorado potato-beetle (Doryphora decemli neata) . a, eggs; b, 

 larva ; c, pupa ; rf, adult. 



from each other larva, pupa, and adult. These are exem- 

 plified in the beetle and butterfly. 



These two classifications do not agree, as can be seen from 

 the following tables : 



MAKDIBULAT^;. HAUSTELLAT.^. 



Thysanura. Hymenoptera.* 



Orthoptera. Hemiptera. 



Pseudoneuroptera. Lepidoptera. 



Neuroptera. Diptera. 



Coleoptera. 



* The Hymenoptera have the mouth-parts adapted for both biting 

 and sucking. 



