CLASSIFICATION 25 



sawflies (Tenthredinidae), judging from their resemblance to 

 mecopterous and lepidopterous larvae ; and the simple, maggot- 

 like form of the larvae of ants, bees, wasps and parasitic 

 Hymenoptera is due to secondary modifications in correlation 

 with their sedentary mode of life. 



In Diptera and Hymenoptera the phenomenon of metamor- 

 phosis attains its greatest complexity, as was remarked. 

 Opinions differ as to which of these two orders is the more 

 specialized. Hymenoptera are commonly called the " high- 

 est " insects, when their remarkable psychological development 

 is taken into account; but from a purely structural standpoint 

 it is hard to say which order is the more complex indeed, the 

 two orders are specialized in so many different ways that no 

 precise comparison can be made between them. 



The following diagram (Fig. 32) is a graphic summary of 

 what has just been said in regard to the genealogy of the 



FIG. 32. 



/&* 



^ V 



% i ** 



* 



SIPHONAPTERA 

 THYSANOPTERA 



HEMIPTERA 

 COLLEMBOLA 



COLEOPTERA THYSANURA 



Genealogical diagram of the orders of insects. 



orders of insects. The positions of Hemiptera and Coleoptera 

 are most open to criticism. The central group (7") is the 



