CHAPTER II 



CLASS HEXAPODA 



The Insects 



The members of this class are air-breathing Arthropoda, with distinct 

 head, thorax, and abdomen. They have one pair of antennce, threee pairs of 

 legs, and usually one or two pairs of wings in the adult state. The opening 

 of the reproductive organs is near the caudal end of the body. 



There are about us on every side myriads of tiny creatures that are 

 commonly passed unnoticed, and even when observed, they are usually 

 thought to be unworthy of serious consideration. But all life is linked 

 together in such a way that no part of the chain is unimportant. Fre- 

 quently the action of some of these minute beings seriously affects the 

 material success or failure of a great commonwealth. The introduction 

 and spread of a single species of insect (the cottony-cushion scale) in 

 California threatened the destruction of the extensive orchards of that 

 State; thousands of trees perished. The introduction of a few individuals 

 of a particular kind of lady-bug (Rodolia cardinalis), which feeds upon 

 this pest and multiplies rapidly, soon checked the pest, and averted the 

 disaster. 



But insects are of interest to us for other reasons than the influence 

 they may have upon our material welfare ; the study of them is a fruitful 

 field for intellectual growth. It is not a small matter to be able to view 

 intelligently the facts presented by the insect world, to know something 

 of what is going on around us. And so extensive and complex is this 

 field that no one gains more than a mere smattering concerning it. 



We know as yet comparatively little about the minute structure of 

 insects; the transformations and habits of the greater number of species 

 have not been studied; and the blood-relationship of the various groups 

 of insects is very imperfectly understood. If, therefore, one would learn 

 something of the action of the laws that govern the life and development 

 of organized beings, and at the same time experience the pleasure de- 

 rived from original investigation, he cannot find a better field than is 

 offered by the study of insects. 



But it is not necessary that one should have the tastes and leisure 

 required for careful scientific investigation in order to profit by this study. 

 It can be made a recreation, a source of entertainment when we are tired, 

 a pleasant occupation for our thoughts when we walk. Any one can find 

 out something new regarding insect architecture — the ways in which 

 these creatures build nests for themselves or for their young. It is easy 

 to observe remarkable feats of engineering, wonderful industry, unremit- 

 ting care of young, tragedies, and even war and slavery. 



The abundance of insects makes it easy to study them. They can be 

 found wherever man can live, and at all seasons. This abundance is even 

 greater than is commonly supposed. The number of individuals in a 



