FOOD OF INSECTS. 257 



true eggs ; and their analogy with the pedunculated eggs of Trombidium 

 aquaticum, which also seem to derive nourishment from the water-boat- 

 men, &.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 animals 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, Hymenojptcra, and Orthoptera, and the larvae of Lepi- 

 dojptera, some Diptera, Stc.) are furnished with jaws, but of very different 

 constructions, and all admirably 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 knawing 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 horizon- 

 tally, not vertically ; 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 requires 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 provided with 

 an organ exquisitely fitted for its office — a slender tubular tongue, more or 

 less long, sometimes not shorter than three inches, but spirally convoluted 

 when at rest, like the mainspring of a watch, into a convenient com- 

 pass. This tongue, which they have the power of instantly unrolling, 

 they dart into the bottom of a flower, and, as though a siphon, draw up a 

 supply of the delicious nectar on which they feed. A letter would 

 scarcely suffice for describing fully the admirable structure of this organ. 

 I must content myself, therefore, with here briefly observing that it is of a 

 cartilaginous substance, and apparently composed of a series of innumer- 

 able rings, which, to be capable of such rapid convolution, must be moved 

 by an equal number of distinct muscles; and that, though seemingly 

 simple, it is in fact composed of three distinct tubes — the two lateral ones 

 cylindrical and entire, intended, as Reaumur thinks, for the reception of 

 air, and the intermediate one, through which alone the honey is conveyed, 

 nearly square, and formed of two separate grooves projecting from the 

 lateral tubes; which grooves, by means of a most curious apparatus of 

 hooks like those in the laminae of a feather, inosculate into each other, 

 and can be either united into an air-tight canal, or be instantly separated, 

 at the pleasure of the insect.^ 



Another numerous race, the whole of the order Hemiptera, abstract the 



» De Geer, vii. 126. 



* For a full desciption of this instrument, s?e Reaum. i. 125, Ace. 



22* 



