60 



APPLIED ENTOMOLOGY 



comparatively small, wingless, and with practically no metamorphosis. 

 After a time many of their descendants began to develop wings, and a 

 fork of the Class was produced, one branch (or Subclass), the Apterygota, 

 apparently retaining much of its former character, while the other sub- 

 class became the Pterygota or winged insects. These have increased 

 greatly in abundance, and their variations have resulted in the produc- 

 tion of many branches passing outward toward the twigs, named in 

 sequence, Orders, Families, Genera and Species. Intermediate branch- 

 ings between these often also need recognition and are called Suborders, 



Mecopi-era- 



Ho mop fere?- - - 

 Jizmipfera 



Anoplura 



Malfaphaga--*, 

 Corrode ntf a- 



HexQpod 



/ Siphonapfara 



inchop-rera 



Sfrepsip'farcr 

 Cokophra 



'Dermaphra 



'Emb'iidina 

 "Pkcophra 



Ephemerida 



f-'TTiusarwra 



Collembo/a 



FIG. 34. Diagram suggesting possible relations of the orders of insects to each other, 

 expressed in a tree-like way: the Hexapod limb. 



Superfamilies, etc., as may be necessary. The twigs each represent a 

 single species, but here we may recognize subspecies, varieties, races, etc., 

 among which the individuals which together constitute the species, are 

 distributed. 



In any consideration of the different groups of insects one must 

 necessarily follow after another through the book, and when four groups 

 for example, are equally near relatives, the first and fourth treated may 

 thereby appear more distant than is really the case. 



Between the fork of the insect limb which produced the Apterygota 

 and the Pterygota, and the twigs representing the species, the actual 



