CHAPTER V 

 THE LOWER ORDERS 



UNDER the general heading of the lower orders may be 

 considered all the less important forms which do not have 

 apparently close relationships. They are widely different 

 in structure and habits and are so grouped for the sake 

 of convenience only. 



27. Thysanura. Thysanura are the most primitive of 

 insects. They have no wings and their mouth-parts are 

 of very rudimentary nature, adapted only for chewing soft 

 substances .or for feeding superficially on dried matter. 

 They have no compound eyes. On the tip of the ab- 

 domen are appendages of some sort, either filaments or 

 modifications of the same which enable the insects to 

 leap considerable distances. Those with the filaments are 

 known as Bristle-tails, while the others are called Spring- 

 tails. They may have, also, rudimentary appendages on 

 nearly all the segments of the abdomen. The most com- 

 mon of the bristle-tails is called the Fish-moth or silver- 

 fish. (Fig. 21, 1.) It is found in houses, in the pantries or 

 bathrooms or in rooms where the wall paper is loose. 

 It feeds on starchy material such as the dried paste be- 

 neath the paper and on some foods, and may be listed 

 as a minor household pest. This insect is of a silvery 

 color and is covered with minute scales. 



Several spring-tails are common, but, on account of 

 their small size, are not noticed. One of these may be 

 found, especially in the early spring, beneath the loose 



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