CHAPTER III. 

 THE ORDERS OF THE HEXAPODA. 



In a preceding chapter the distinguishing characters of insects 

 have been discussed. We have now to study the manner in which 

 the class Hexapoda is divided into its principal divisions or orders. 

 Regarding this subject, there is at the present time much difference 

 of opinion. Naturalists are not agreed as to the limits of the differ- 

 ent orders of insects. The number recognized in standard works 

 varies from seven to more than twice that number. 



Although the question is an exceedingly difficult one, it is an 

 easy matter to state where the differences of opinion lie. And these 

 differences do not complicate the subject greatly. 



More than a century ago Linnaeus recognized seven orders of 

 insects. These he named Coleoptera, Hemiptera, Lepidoptera, 

 Neuroptera, Hymenoptera, Diptera, and Aptera. Five of these 

 orders were well founded ; and two were not. The Aptera was soon 

 regarded as an unnatural group. It included various wingless in- 

 sects, which later entomologists have distributed among the other 

 orders. The Linnaean order Hemiptera included all four-winged in- 

 sects in which the front wings are half horny and half membranous. 

 But here Linnaeus by confining his attention to the wing characters 

 alone fell into error. The order Hemiptera as defined by him in- 

 cluded at least two distinct orders ; and those members of it with 

 biting mouth-parts were separated a little later by Olivier as the 

 order Orthoptera. Thus by the suppression of the Aptera, and the 

 erection of the Orthoptera, the number of orders remained the same 

 as proposed by Linnaeus. And with these two modifications the 

 Linnaean classification has been very generally accepted to this day. 



The modified Linnaean system indicated above is very simple 

 and for this reason many entomologists are loath to propose alter- 

 ations in it. But there are certain places in which this classification 

 brings together insects which differ too widely to be classed in the 

 same order. The science of Entomology, however, is not yet far 

 enough advanced for any one to state with any degree of certainty 

 in just how many cases this is true. 



One of the principal points in which there are differences of 



