436 MOTIONS OF INSECTS. 



(Hypera Rumicis) has twenty-four tubercular legs : but, what is remarkable, 

 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. 1 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. 2 



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

 fly described by De Geer ( Volucella plumata) 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. 3 



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

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

 a traveller 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 witnesses, 

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

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

 Quercus 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 pro- 

 tuberance 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. 4 So wisely has Providence ordered every thing. Another 

 similar instance is recorded by De Geer, which indeed had been previously 

 noticed, though cursorily, by the illustrious Frenchman. 5 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 meal of the various 

 species of animalcula, abounding in stagnant waters, that come within the 



i De Geer, v. 233. 2 ibid. v. 228. 



5 Ibid. vi. 137. t. viii. f. 8, 9. 4 R ea um. iii. 496. t. xlv. f. 3. 



5 Ibid. Mem. de I'Acad. Roy. des Sciences de Paris, An. 1714. p. 203. 



