TOOD OF INSECTS. 393 



verted to (Nycierobius) are remarkable for providing in 

 the night a store of food which they consume in the day ; 

 but to the generality of these the period of feeding is in- 

 different, and most of them seem to eat with little inter- 

 mission night and day. 



Insects like other animals take in their food by the 

 mouth (in Chermes and Coccus, indeed, the rostrum seems 

 to be inserted in the breast, between the fore-legs), but 

 there is one exception to this rule. The singular Acarus 

 vegetans, which is such a plague to some beetles, derives 

 its nutriment from them by means of a filiform pedicle or 

 umbilical cord attached to its anus ; and what increases 

 the singularity, sometimes several of these Acari form a 

 kind of chain, of which the first only is fixed by its pedicle 

 to the beetle, each of the remainder being similarly con- 

 nected with the one that precedes it ; so that the nutri- 

 ment drawn from the beetle passes to the last through the 

 bodies and umbilical cords of the individuals which are 

 intermediate a . Some have regarded these bodies as true 

 eggs ; and their analogy with the pedunculated eggs of 

 Trombidium aquaticum, F., which also seem to derive nou- 

 rishment from the Notonectse, &c. to which they are fixed, 

 and still more the circumstance of their ultimately losing 

 their pedicle and detaching themselves from the infested 

 beetles, give plausibility to the idea. Yet these Acari 

 are certainly furnished with feet, and have according to 

 De Geer b a part resembling a mouth — characters which 

 cannot be attributed to any egg. 



In the variety of their instruments of nutrition, which 



* De Geer,vii. 123. . » Id. ibid. }26. 



