AN INTRODUCTION TO ENTOMOLOGY. 



CHAPTER I. 



THE CHARACTERS AND METAMORPHOSES OF INSECTS 

 (HEXAPODA). 



I. THE CHARACTERS OF THE HEXAPODA. 



Tin: term Insect is from two Latin words /';/, in, and scco, to cut. 

 It refers to the fact that in the animals indicated by it the body is 

 divided by transverse incisions into a series of segments. As has 

 been shown in the Introductory Chapter, this insected form of the 

 body is characteristic of two of the larger divisions of the Animal 

 Kingdom, the Vcrmcs, or Worms and the Arthropoda. But the term 

 Insect has become restricted to a portion of this great series of ani- 

 mals. There is, however, a lack of uniformity in the use of the term 

 among zoological writers. By some it is applied to all Arthropoda 

 that breathe by means of a system of air-tubes (trachea) extending 

 throughout the body. This includes Centipedes, Millepedes, Spi 

 and allied forms, as well as the six-footed insects. Other writers in- 

 clude among Insects only those orders which are characterized by 

 the possession of but six legs. It is in this restricted sense that I 

 have u>ed the term Insect. Whenever reference is made to all of the 

 Arthropoda that breathe by means of tracheae, they are designated 

 as the Trncli-. 



in the restricted sense indicated above, constitute the 



. IDA.* The inserted or 



rm of the body is shown 



i. and in nearly all of the 



species figured mth< following pages. 



f the respira- 



tory system, wh , uu 



animals, and which allies them 



s described in the next chapter [nthc 1 1. \apoda 



xlpoda : *<*(*&, fix; pout (jrovf), a foot. 



