FOOD OF INSECTS. 393 



anus ; and what increases the singularity, sometimes se- 

 veral of these mites 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 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 Tromlidium aquaticum, 

 which also seem to derive nourishment from the water- 

 boatmen, &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 plau- 

 sibility to the idea. Yet these animals are certainly fur- 

 nished with feet, and have according to De Geer b a part 

 resembling a mouth characters which cannot be attri- 

 buted to any egg. 



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 

 far behind. In common with them, a vast number (the 

 orders Coleoptera, Hymenoptera^ and Orthoptera, and the 

 larvae of Lepidoptera, some Diptera, &c.) are furnished 

 with jaws, but of very different constructions, and all ad- 

 mirably adapted for their intended services ; some sharp, 

 and armed with spines and branches for tearing flesh ; 

 others hooked for seizing, and at the same time hollow 

 for suction ; some calculated like shears for gnawing 

 leaves; others more resembling grindstones, of a strength 

 and solidity sufficient to reduce the hardest wood to pow- 

 der : and this singularity attends the major part of these 



a De Geer, vii. 123. b Id. ibid. 126. 



