CHAPTER III 

 THE CLASSIFICATION OF INSECTS 



As has been explained in the preceding chapter, insects are primarily classi- 

 fied on the basis of their postembryonic development. Insects with incom- 

 plete metamorphosis, that is, those which do not undergo a non-feeding, 

 usually quiescent, pupal stage in their development are believed to be more 

 nearly related to each other than to any of the insects which undergo a so- 

 called complete metamorphosis. So they are spoken of collectively as the 

 Hemimetabola, while all the insects with a distinct pupal stage are called 

 the Holometabola. But when one has collected an adult insect, as a fly 

 or moth or grasshopper, and wishes to classify it, this primary classification 

 based on character of development often cannot be made for lack of informa- 

 tion regarding the life-history of the particular insect in hand. The next 

 grouping is into orders, and this grouping is based chiefly on structural 

 characters, and corresponds to one's already more or less familiar knowledge 

 of insect classification. Thus all the beetles with their horny fore wings 

 constitute one order, the Coleoptera; the moths and butterflies with their 

 scale-covered wings another order, the Lepidoptera; the two- winged flies 

 the order Diptera, the ants, bees, wasps, and four-winged parasitic flies 

 the order Hymenoptera, and so on. So that the first step in a beginner's 

 attempt to classify his collected insects is to refer them to their proper orders. 



Now while entomologists are mostly agreed w!th regard to the make-up 

 of the larger and best represented orders, that is, those orders containing 

 the more abundant and familiar insects, there are certain usually small, 

 obscure, strangely formed and more or less imperfectly known insects with 

 regard to whose ordinal classification the agreement is not so uniform. While 

 some entomologists incline to look on them simply as modified and aberrant 

 members of the various large and familiar orders, others prefer to indicate 

 the structural differences and the classific importance of these differences 

 by establishing new orders for each of these small aberrant groups. Most 

 entomologists of the present incline toward this latter position, so that whereas 

 Linnaeus, the first great classifier of animals, divided all insects into but 

 seven orders, the principal modern American * text-book of systematic ento- 



* Comstock, J. H., A Manual of Insects, 1898. 



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