490 GEOGRAPHICAL DISTRIBUTION OF INSECTS. 



in our cabinets % we may very reasonably infer that at 

 least three fourths of the existing species remain undis- 

 covered. 



Certain groups and genera are found to contain many 

 more species than others : for instance, the Coleoptera 

 and Lepidoptera Orders than the Orthoptera and Neu- 

 r opt era , the Rhincophora than the Xylophagi ; the Dy- 

 tiscidce than the Gyrinida ; Aphodius than Geotrupes ; 

 Carabus than Calosoma. Again, some insects are much 

 more prolific than others. Thus the Diptera Order, 

 though not half so numerous with respect to species 

 as the Coleoptera^ exceeds it greatly in the number 

 of individuals, filling the air in every place and almost 

 at every season with its dancing myriads. We rarely 

 meet with a single individual of the most common spe- 

 cies of Calosoma or Buprestis; whilst the formicary, the 

 termitary, the vespiary, and the bee-hive send forth 

 their thousands and tens of thousands ; and whole coun- 

 tries are covered and devastated by the Aphides and the 

 Locusts. An all-wise PROVIDENCE has proportioned 

 the numbers of each group and species to the work as- 

 signed to them. And this is the view in which the nu- 

 merical distribution of insects is most interesting and 

 important : and we are indebted to Mr. W. S. MacLeay 

 for calling the attention of Entomologists more particu- 

 larly to this part of our present subject. 



With regard to their functions, insects may be pri- 

 marily divided into those that feed upon animal matter 

 and those that feed upon vegetable. At first you would 

 be inclined to suppose that the latter must greatly ex- 



a Ho)\ Entomolog. 469. This calculation includes the Crustacea. 



