SPECIES INJURIOUS TO WALL PAPER, BOOKS, ETC. 



70 



THE BOOK-LOUSE. 



{AtropoH dirinaloria Fab.) 



This pale, louse-like insect, measuring less than 1 mm. in length, usu- 

 ally occurs in houses, though rarely in any numbers, and is most often 

 seen on opening old musty volumes, scampering across the page to con- 

 ceal itself elsewhere. From this habit comes its j)opular name of book- 

 louse. It is one of the smallest of insects, nearly colorless, and almost 

 invisible to the unaided eye, except as its active movements attract 

 one's attention. It belongs to the family Psocidai, and is somewhat 

 closely allied to the white ants, belonging in the same order. There are 

 a number of species of psocids which frequent houses, all popularly 

 styled book-lice, and having habits and characteristics very similar to 

 the one named above, which is the more common and annoying species. 



Fig. 34. — Atroj>oK divinatoria: a, adult from below; b, sainc IVoni above: /, iiiiixill;u v palpus; e. max- 

 illa (?); ci, mandible; c, labium— all enlarjred (original). 



and maybe taken as the type. All these troublesome house si)ecies are 

 soft-bodied, wingless, degraded creatures, representing the very lowest 

 form of insect life. A great many species, also, live out of doors, many 

 of these being winged and somewhat resembling i)lant-lice. They fre- 

 quently occur in numbers on the bark of trees and tlie walls of buildings, 

 and feed on lichens or decaying vegetable matter. The Psocida* are 

 biting insects, having well-developed mandibles and other mouth parts. 

 One of the most interesting features in connection witli the common 

 house species, and from which it takes sometimes the name "death 

 watch," is the reputation it has of making a ticking sound, supposed to 

 prognosticate dire consequences to some inmate of the house. That it 

 can make some such noise, })robably by striking its head against some 

 hard object, seems to be pretty well established in spite of the seeming 



