INVESTIGATION OF INSECTS. 35 



of animals, and particularly of insects, in the mass; for 

 though the knowledge of species, as Mr. Kirby has well ob- 

 served, is indispensable for the registry of facts and other 

 practical purposes, yet the knowledge of groups leads to a 

 higher wisdom ; and indeed it is through these that we best 

 descend to the study of species. The first thing, therefore, 

 requisite is, to ascertain to what order of insects any indi- 

 vidual specimen may belong. For this purpose an inspection 

 of the mouth (for the purpose of ascertaining whether it is 

 furnished with jaws or with a sucker), and of the structure 

 of the wings, will generally suffice. The next step is the 

 separation of your collection into the primary sections and 

 families of which the orders are composed; and here, of 

 course, the characters will vary in the different orders ; for 

 instance, in the order of beetles (Coleoptera), the primary 

 sections are founded upon the variations in the number of 

 joints in the tarsi (or last articulated part of the leg) ; 

 whereas in the two-winged flies {Diptera) this character is 

 constant, and the number of joints in the antennae consti- 

 tute the leading characters of the primary divisions. For 

 the families, no better rule could be laid down than to study 

 the characters of the Linnajan genera, which in fact corres- 

 pond generally with the modern famihes of insects ; but, as 

 will be more fully detailed in a subsequent page, the con- 

 tents of these groups have so immensely increased since 

 the days of Linnaeus, that it has become necessary to sub- 

 divide them into minor divisions, to which the names of 

 genera and sub-genera have been given ; and here it will be 

 necessary to have recourse to such authors as Fabricius and 

 Latreille, Stephens or Curtis, for obtaining an idea of the 

 extent to which these subdivisions have been cai'ried, as well 

 as for obtaining a knowledge of the various subdivisions 

 themselves. The practised eye, indeed, can readily reduce 

 an extensive family of insects into its sectional groups, without 



