82 AN INTRODUCTION TO ENTOMOLOGY. 



tally pine, from near the trees; as such wood is liab'. 

 become infested, and the white ants to spread from it to the orar. 

 trees. 



The zoological position of the Termitidae is, like that of the Eplu'im 

 near the foot of the insect series. In fact, the form of the win-s with Ttnnes 

 i^arded as even more primitive than that of A/ /////</ i / as is also the 

 structure of the thorax, with its equally developed and unusually distinct 

 ments. But the wonderful development of instinctive powers and of separate 

 castes among the whitr-ants indicates that, although ;is shown by their Mrur 

 tu re. they represent one of the lowest groups of winged insects preserve 

 this time, they constitute the highest development of their line. It is a sug- 

 gestive fact that Hagen, who is the best informed regarding the Termii 

 considers them closely related to the Blattidae, to which the oldest known in- 

 sects belong. 



Family V. PSOCID/E.* 



(Book-lice ct al.) 



The best known representatives of this family are the minute in- 

 sects common in old papers, books, and neglected collections ; and 



which have received the name of Book-lice. 

 These low, wingless creatures form, how- 

 ever, but a small part of the family. The 

 more typical and winged forms 



a strong resemblance to plant-lice or 

 Aphides. The body is oval, the head free. 

 and the prothorax is small. The wings 

 when present arc of unequal size, the hind 



Pic. 77. Ptflctu venosus. . 



pair being smaller. When not in use the 



wings are folded roof-like over the body, like those of the Aphides. 

 The tarsi are two- or three-jointed. 



There are two sub-families, which are distinguished as foll< 



A. Ocelli wanting; wings absent or incomplete. A J 



AA. Ocelli present; wings well developed. IN.*. 



ATROPLN ? ^:. Two genera of this sub-family are represented in 

 this country. In Atropos the wings are absent, the ineso- and 

 athorax are grown together, and the antenna; are seventeen- 

 jointed. The common Book-loust fos dii-inatoria. This species 



i> about I mm. in length ; it is grayish white, with black eyes. Closely 

 allied to this genus is ClotJiilla, in which the anterior wings are rep- 

 uted by small convex scales ; the meso and metathorax are free, 

 and the antennae are many-jointed. 



*Ps6cul2e, PsOcus : psocho (#<;r<), to grind. 



