FOOD OF INSECTS. 395 



which alone the honey is conveyed, nearly square, and 

 formed of two separate grooves projecting from the late- 

 ral 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 plea- 

 sure of the insect^. 



Another numerous race, the whole of the order He- 

 mipteroy abstract the juices of plants or of animals by 

 means of an instrument of a construction altogether dif- 

 ferent — a hollow grooved beak, often jointed, and con- 

 taining three bristle-formed lancets, which, at the same 

 time that they pierce the food, apply to each other so 

 accurately as to form one air-tight tube, through which 

 the little animals suck up'' their. repast; thus, forming a 

 pump, which, more effective than ours, digs the well 

 from which it draws the fluid "=. 



A third description of hisects, those of the order Di- 

 ptera, comprising the whole tribe of flies, have a sucker 

 formed on the same general plan as that last described, 

 but of a much more complicated and varied structure. 

 It is in like manner composed of a grooved case and 

 several included lancets ; but the case, although horny, 

 rigid and beak-like in some, is in others fleshy, flexible, 



" For a full description of this instrument see Reaiim. i. 125, &c. 

 Plate VI. Fig. 13. 



^ The mode, however, in which this is effected in all insects fur- 

 nished with a proboscis, can scarcely be by suction, strictly so called, 

 or the abstraction of air, since the air-vessels of insects do not com- 

 municate with their mouths : it is more probably performed in part 

 by capillary attraction ; and, as Lamarck has suggested, {Syst. dcs 

 Anim. sans Vertcbres, p. 193.) in part by a succession of undulations 

 and contractions of the sides of the organ. 



' Plate VI. Fig. 16-^19. 



