8 4 



THE STUDY OF INSECTS 



The psocids occur upon the trunks and leaves of trees, and on stones, 

 walls, and fences. They feed upon lichens, fungi, and probably other 

 dry vegetable matter. 



The eggs are laid in heaps on leaves, branches, and the bark of trunks 

 of trees. The female covers them with a tissue of threads, the silk of 

 which is spun from the labium. 



Family Atropid^e 



The Book-lice and their Allies 



The most commonly observed species of this family are those known 

 as book-lice, which are the minute soft-bodied insects often 

 found in old books (Fig. 133). 



Take down from the shelf a time-yellowed book and 

 open its neglected leaves and watch the pale tiny creatures 

 that scurry across its pages; examine one of them with a 

 lens, look well at its alert, knowing, black eyes, and we are 

 sure you will believe that it is in search of real literature and 

 not merely a feeder upon paper, as we are taught. Anyway, 

 scientists have concluded that these insects look wise 

 enough to bear the name Troctes divinatorius. Another 

 species with small convex scales representing the front wings is Atropos 

 pulsatoria. It is pale yellowish white and only ^ s of an inch in length. 



The book-lice feed on the paste in bookbindings, wall-paper and 

 photographs. One species sometimes occurs in enormous numbers in 

 husk or straw mattresses, in which case it is very annoying. 



Fig. 133. — A book 

 louse. 



/?4+5 



Fig. 133a. — Wings of a psocid. 



These enlarged wings of a psocid illustrate the anastomosing of the 

 principal veins, a form of structure which strengthens the wings with- 

 out the necessity of cross-veins. 



