BEETLES, BOOKWORMS AND DEATH-WATCHES 229 



which may be briefly described as a minute tailless scorpion, 

 is also to be found among neglected books, where it pursues 

 its prey. 



So many insects attack large collections of books, and 

 so great is the damage done by them, that it is part of 

 the professional education of the librarian to know the 

 marks by which the different kinds are recognised, and 

 the methods of extermination appropriate to each. Fifty 

 or sixty book-destroying insects and mites have been 

 catalogued, and books have been written to describe 

 them, and explain how they are to be combated. 1 



Just as there are several different kinds of bookworms, 

 there are several kinds of death-watches. Small insects 

 (Atropos), belonging to the family of Psocidae, and believed 

 to be allied to White Ants, make a ticking very like that 

 of Anobium. Two species of Atropos are common in our 

 houses, frequenting dusty recesses, neglected straw, old 

 papers, picture-frames, &c. They are often found on wall- 

 paper. Both are so small as to require a lens to identify 

 them. One kind (A. divinatoria) can be recognised by 

 the vestiges of wings, which project as scales from the 

 middle of the thorax ; it has larger eyes than the other 

 species, its length does not exceed I mm., and the legs 

 of the third pair are much dilated at their bases. The 

 second kind (A. pulsatoria) is larger (nearly 2 mm. long), 

 devoid of wings, and its eyes are minute. It is this second 

 kind of death-watch which makes such havoc in neglected 

 collections of insects. Both divinatoria and pulsatoria 

 produce a ticking sound, which is liable to be mistaken 

 for the call of an Anobium. It has been said that Atropos 

 has no structures in its body sufficiently hard to produce 

 an audible sound, and that even when the ticking sound 

 is heard and the Atropos discovered, it is really an unseen 

 Anobium from which the sound proceeded. But the 



1 Blades on 7'he enemies of books is a well-known English treatise. 

 The latest study of bookworms is Dr. Houlbert's Insectes enneinis des 

 Livres, Paris, 1903. 



