MOTIONS OF INSECTS. 277 



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 ver- 

 tical *. But the iireatest number of legs of this kind 

 that distinguish any known larva, is to be observed in 

 that of a two-winged fly [Si/rphus Pyrastri) that de- 

 vours 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''. — The 

 grub of the weevil of the dock [Hi/pera 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, how- 

 ever, 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 fall- 

 ing'^. Another weevil {Livus 2'>(if'^pl(^clicus,) produces 

 a grub inhabiting the water-hemlock, which has only 

 six tubercles that occupy the place and are represen- 

 tatives of the legs of the perfect insect '^. 



Some larvae have these tubercles armed with claws. 

 The maggot of a fly described by De Geer ( Volucdla 

 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 ^. 



Insects in the peculiarities of their structure, as we 

 have seen in many instances, sometimes realize the wild- 



=■ De Geer, i. 447 — /• xxxi. /. 17. '' De Geer, vi. 111. 



' Ibid. V. 233. " Ibid. 228. - De Geer, vi. 137- 1, viii./. 8, 9. 



