FOOD OF INSECTS. 



331 



passes to the last through the bodies and umbilical cords of 

 the individuals which are intermediate.^ Some have regarded 

 these bodies as true eggs ; and their analogy with the pedun- 

 culated eggs of Trombidium aquaticum, which also seem to 

 derive nourishment from the water-boatmen, &c., to which 

 they are fixed^ and still more the circumstance of their ulti- 

 mately losing their pedicle and detaching themselves from the 

 infested beetles^ give plausibility to the idea. Yet these ani- 

 mals are certainly furnished with feet, and have, according 

 to De Geer^, a part resembling a mouth — characters which 

 cannot be attributed 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 dif- 

 ferent constructions, and all admirably adapted for their in- 

 tended 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 powder: and this singularity attends the major part of 

 these insects, that they possess in fact two pairs of jaws, an 

 upper and an under pair, both placed horizontally, not ver- 

 tically ; the former apparently in most cases for the seizure 

 and mastication of their prey ; the latter, when hooked, for 

 retaining and tearing, while the upper comminute it previously 

 to its being swallowed. 



To the remainder of the class of insects, a mighty host, 

 jaws would have been useless. Their refined liquid food re- 

 quires instruments of a different construction, and with these 

 they are profusely furnished. The innumerable tribes of 

 moths and butterflies eat nothing but the honey secreted in 

 the nectaries of flowers, which are frequently situated at the 

 bottom of a tube of great length. They are accordingly pro- 

 vided with an organ exquisitely fitted for its office — a slender 



1 De Geer, vii. 123. 2 Id. ibid. 126. 



