226 



MOTIONS OF INSECTS. 



this larva uses these two legs much as the caterpillars of the 

 moths, called Geometrce, do theirs. By the inflection of the 

 anus it can give them any kind of lateral movement, except 

 that it can neither bend nor shorten them, since like a wooden 

 leg, as I have before observed, they always remain stiff and 

 extended. 1 Lyonet had observed this larva, or a species 

 nearly related to it ; but he speaks of it as having four legs, 

 two before and two behind. Probably, when he examined 

 them, the common base, from which the feet are branches, 

 was retracted within the body. 2 



Generally speaking, however, in these apodous walkers the 

 place of legs is supplied by fleshy and often retractile ma- 

 millae or tubercles. By means of these and a slimy secretion, 

 unaided by mandibular hooks, the caterpillar of a little moth 

 (Apoda Testudo) moves from place to place. 3 A subcuta- 

 neous larva belonging to the same order, that mines the leaves 

 of the rose, moves also by tubercular legs assisted by slime. 

 It has eighteen homogeneous legs, with which, when removed 

 from its house of concealment, it will walk well upon any 

 surface, whether horizontal, inclined, or even vertical. 4 But 

 the greatest number of legs of this kind that distinguish any 

 known larva is to be observed in that of a two-winged fly 

 (Scceva Pyrastri) that devours the Aphides of the rose. This 

 animal has six rows of tubercular feet, with which it moves, 

 each row consisting of seven, making in all forty-two. 5 The 

 grub of the weevil of the dock (Hyper a 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 lepidop- 

 terous 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. 6 Another weevil (Lixus paraplecticus) 



1 De Geer, vi. 395. Mr. W. S. MacLeay is of opinion that these legs are 

 pedunculated spiracles (Philos. Mag. N. Series, No. 9. 178.); but it is evident 

 from De Geer's account that the animal uses them as legs, and like legs they are 

 armed with hooks or claws. 



3 Lesser, 1. i. 96. notef. 3 Klemann, Beitrage, 324. 



4 De Geer,i. 447. t. xxxi.f. 17. 5 De Geer, vi. 111. 

 6 Ibid. v. 233. 



