. I \ 



Iar\-;r, with eleven <>r twelve pairs nf legs, suggest affinities with Lepidop- 

 md, more remotely, with the tent hredinid Hyinenopfera. Mecop- 

 tera ;ire most nearly related to N'etiroptera dhroi: Ifl Nemop- 



lcr,i) and have also Certain affmhies with hiptera i ( 'rainpl on). 



Trichoptera, while much like Mecopt I meta- 



morphosis, are undoubtedly closely related to Lepidopt era ; in view of 

 the extensive and deep sealed resemblances bet: 



the most ^enerali/ed moths ( Micropt* it must he < (.IK luded that 



Trichoptera and Lepidoptera originated from the same stock, which 

 doubtless neuropteroid. 



PLEGOPTERA 

 PLATYPTERA 



ORTHOPTERA 



/x 



SIPHONAPTERA 



THYSANOPTERA 



KEMIPTERA 



THYSANURA 



COLEOPTERA 



FIG. 33. Genealogical diagram of the orders of insects. 



Hymenoptera also trace their ancestry back to neuropteroid forms. 

 The most generalized hymenopterous larvae, those of saw-flies, are 

 caterpillar-like; but the most specialized larvae, as those of ants, bees, 

 wasps, and parasitic Hymenoptera, are more like maggots, in correlation 

 with their sedentary mode of life. 



Hymenoptera are often called the " highest" insects, chiefly on 

 account of their highly developed instincts and social life. From this 

 point of view, however, the termites also would rank high, though 

 structurally they belong among the more generalized insects. Afl 

 matter of fact, the system of classification is based necessarily on 

 structure, and not on psychology; and structurally Hymenoptera are, 

 taking everything into consideration, less specialized than Dipt era. 



In Diptera the cruciform type of larva attains its extreme degree of 



