POOD OF INSECTS. 393 



food which they consume in the day ; but to the gene- 

 rality of these the period of feeding is indifferent, and 

 most of them seem to eat with little intermission night 

 and day. 



Insects like other animals take in their food by the 

 mouth (in Chermes and Coccus^ indeed, the rostrum 

 is inserted in the breast, between the fore-legs), but 

 there seems one exception to this rule. The singular 

 Acarus vegetans, which is such a plague to some bee- 

 tles, 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 connected with the one that 

 precedes it; so that the nutriment drawn from the 

 beetle passes to the last through the bodies and umbi- 

 lical cords of the individuals which are intermediate^. 

 Some have regarded these bodies as true eggs ; and 

 their analogy with the pedunculated eggs of Trombi- 

 d'mm aquaticitm, F., which also seem to derive nou- 

 rishment from the Notonecta^, &c. to which they are 

 fixed, aiid 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 ac- 

 cording to De Geer'' a part resembling a mouth — cha- 

 racters ^.Yhicli cannot be attributed to any eg^. 



In the variety of their instruments of nutrition, which 

 you must bear in mind are often quite different in the 

 larva and perfect states, insects leave all other animals 



^ De Gcer, vii, 123, " Ibid. vii. 126. 



