160 Dr. Johnston on the Acarides of Berwickshire. 



armed with scattered bristles, of which those on the anal edge 

 are the longest. Rostrum declivous, obtuse, armed with man- 

 dibles at the apex. Front with several bristles, two of them long 

 and porrect. Legs eight, much shorter than the body, in two 

 sets, colourless, subcylindrical, bristly, armed with a long bristle 

 at the tibial joint; the tarsi with short stout bristles and claws; 

 the anterior pair of legs are stouter than the posterior, and equal 

 in size and length ; the third pair longer than the fourth, which 

 are the shortest of any. 



This differs from Ac. lectis in being narrower behind, in the 

 legs being proportionally shorter, in the colourless hue of the 

 rostrum and legs, in having the last pair of legs shorter than 

 the third pair, and in the greater distinctness of the mandibles. 

 I could not discover the tarsal vesicles. The bristles vary in 

 different individuals in length, probably from the points in some 

 having been broken off. In one or two specimens there was a 

 semicircular plate at the anus, from the upper surface of which 

 two bristles originated. The larva? have only six legs. The 

 eggs are elliptical and smooth. 



We virtuosi — the unhappy objects of some happy ridicule — 

 would willingly permit the cheese-mite his full liberty in waste, 

 could we exchange that liberty for the imprisonment of its 

 brother mite, whose peculiar vocation it is to reduce to dust and 

 ashes our cherished insects and skins, and other prized curiosities. 

 No drawer is close enough to exclude him ; and verily oft we in 

 wonder ask, how the devil he got there*. Many recipes have 

 been recommended to prevent its appearance ; but none prove 

 of any avail, although some of them are effectual enough in 

 killing the insects when their presence is detected, usually how- 

 ever with some loss of perfection to the infected specimens -f\ 

 They show a preference to dung-beetles (as Geotrupes, Necro- 

 phagus, Hister, Aphodius, Silpha, &c.) and to humble-bees, 

 which have an abundance of animal matter in their interior ; but 

 they prey upon the entire class of insects. " One of the worst 

 plagues of the entomologist," say Kirby and Spence, " are the 

 mites (Acarus destructor, Schrank.). These, if his specimens be 

 at all damp, eat up all the muscular parts (Lytta vesicatoria 

 being almost the only insect that is not to their taste), and thus 

 entirely destroy them." (Introd. to Entom., i. p. 240.) 



* Thus did the good Antony Van Leeuwenhoek wonder, — " And indeed 

 I have often found mites feeding on things in places where I wondered 

 they could so soon discover their food." (Select Works, ii. p. 39.) 



f As Leeuwenhoek has found that mites greatly dislike nutmeg, and 

 are soon killed by its odour, it might be used to protect insect-drawers. 

 (Select Works, i. p. 289.) 



