22 



more delicate, and when at rest are folded lengthwise like 

 a fan, under the first pair, which serve as covers for them. 

 This straight, longitudinal folding of the wings provides 

 the name of the order, which comes from the two Greek 

 words orthos, straight, and pteron, a wing. The silverfish 

 (see Fig. 8) are for convenience included in this order, 

 although they are wingless. The metamorphosis is incom- 



Fig-. 15. Ortnoptera. 

 Slightly enlarged. 



Grasshopper. 

 (Original.) 



plete ; the mouth parts are formed for biting, in both larvae 

 and adults. 



The silverfish, a common household pest, which is one 

 of the most primitive of insects, should really be included 

 in another order the Thysanura. The members of this order 

 never possess wings ; their mouth parts are formed for biting, 

 but are not powerful ; and their metamorphosis is incomplete. 

 Only one insect of this order is mentioned in this book ; 

 and for the sake of convenience it has been referred to the 

 Orthoptera, which include insects most closely related to 

 the Thysanura. 



Order II. Thysanoptera. Fringe-Winged Insects. 



This order includes the insects known as Thrips. These 

 are small, delicate insects with mouth parts formed for 

 cutting and lapping. The first and second pairs of wdngs are 

 similar in size and shape ; and are bordered with a fringe of 



