PREHENSION OF LIQUID FOOD. 103 



conceives that the lateral tubes are intended for 

 the reception of air, while the central canal conveys 

 the honey, which the insect sucks from flowers, by 

 suddenly unrolling the spiral coil, into which the 

 proboscis is usually folded, and darting it into the 

 nectary.* 



In the Hemiptera, the proboscis is a tube, either 

 straight or jointed, guarded by a sheath, and acting- 

 like a pump. The Diptera have a more compli- 

 cated instrument for suction, consisting of a tube, 

 of which the sides are strong and fleshy, and move- 

 able in every direction, like the trunk of an 

 elephant : it has, at its extremity, a double fold, 

 resembling lips, which are well adapted for suction. 

 The Gnat, and other insects which pierce the skin 

 of animals, have, for this purpose, instruments 

 termed, from their shape and office, lancets.'^ In 

 the gnat they are five or six in number, finer than 

 a hair, exceedingly sharp, and generally barbed on 

 one side: in the Tuhanns, or horse-fly, they are 

 flat, like the blade of a knife. These instruments 

 are sometimes constructed so as to form, by their 

 union, a tube adapted for suction. In the flesh- 

 fly, the proboscis is folded like the letter Z ; the 

 upper angle pointing to the breast, and the lower 

 one to the mouth : in other flies there is a single 

 fold only. 



Those insects of the order Hymenoptera, which, 

 like the Bee, lap up the honey of flowers, have, 

 together with regular jaws, a proboscis formed by 

 the prolongation of the lower lip, which is folded 

 so as to constitute this peculiar organ. It is pro- 



* Kirby and Spence's Entomology, vol. ii. p. 390. 

 t Ibid. vol. iii. p. 467. 



