MOTIONS OF INSECTS. 471 



of seven, making in all forty-two.^ The grub of the weevil of the dock 

 (Hypera Ramicis) has twenty-four tubercular legs ; but, what is remark- 

 able, the six anterior ones, being longer than the rest, seem to represent 

 the real legs, while the others represent the spurious ones, of lepidopterous 

 larvae. These legs, however, are all fleshy tubercles, and have no claws, 

 the place of which is supplied by slime which covers all the underside of 

 the body, and hinders the animal from falling.^ Another weevil {Lixus 

 paraplecticus) produces a grub inhabiting the water-hemlock, which has 

 only six tubercles that occupy the place and are representatives of the 

 legs of the perfect insect.^ 



Some larvae have these tubercles armed with claws. The maggot of a 

 fly described by De Geer (Volucella plaviata) has six pair of them, each 

 of which has three long claws. This animal has a radiated anus, and 

 seems related to those flies that live in the nests of humble-bees.^ 



Insects, in the peculiarities of their structure, as we have seen in many 

 instances, sometimes realize the wildest fictions of the imagination. Should 

 a traveler tell you that he had seen a quadruped whose legs were on its 

 back, you would immediately conclude that he was playing upon your 

 credulity, and had lost all regard to truth. What then will you say to 

 me, when I affirm, upon the evidence of two most unexceptionable wit- 

 nesses, Reaumur and De Geer, that there are insects which exhibit this 

 extraordinary structure ? The grub of a little gall-fly, appearing to be 

 Cynips (^iiercus inferus of Linne, which inhabits a ligneous gall resembling 

 a berry to be met with on the underside of oak-leaves, was found by the 

 former to have on its back, on the middle of each segment, a retractile 

 fleshy protuberance that resembled strikingly the spurious legs of some 

 caterpillars. A little attention will convince any one, argues Reaumur, 

 that the legs of insects circumstanced like the one under consideration, if 

 it has any, should be on its back. For this grub, inhabiting a spherical 

 cavity, in which it lies rolled up as it were in a ring, when it wants to 

 move, will be enabled to do so, in this hollow sphere, with much more 

 facility, by means of legs on the middle of its back, than if they were in 

 their ordinary situation.^ So wisely has Providence ordered every thing. 

 Another similar instance is recorded by De Geer, which indeed had pre- 

 viously been noticed, though cursorily, by the illustrious Frenchman.^ 

 There is a little larva, he observes, to be found at all seasons of the year, 

 the depth of winter excepted, in stagnant waters, which keeps its body 

 always doubled as it were in two, against the sides of ditches or the stalks 

 of aquatic plants. If it is placed in a glass half full of water, it so fixes 

 itself against the sides of it, that its head and tail are in the water while 

 the remainder of the body is out of it ; thus assuming the form of a 

 siphon, the tail end being the longest. When this animal is disposed to 

 feed, it lifts its head and places it horizontally on the surface of the water, 

 so that it forms a right angle with the rest of the body, which always 

 remains in a situation perpendicular to the surface. It then agitates, with 

 vivacity, a couple of brushes, formed of hairs and fixed in the anterior part 

 of the head, which, producing a current towards the mouth, it makes its 



' De Geer, vi. HI. 2 Ibid. v. 233. » ibid. v. 228. 



* Ibid. vi. 137. t. viii. f. 8, 9. s Reaiim. iii. 496. t. xlv. f. 3. 



* Ibid. M6m. de I' Acad. Roy. des Sciences de Paris, An. 1714. p. 203. 



