360 



PHYSIOLOGY. 



from the action of the saliva and the other fluids which flow into the sto- 

 mach: for example, the true Cantharides (Lytta vesicatoria) and Sphinx 

 Ligustri feed upon the same plant, viz., Ligustrum vulgare, Lin., and 

 yet in the Sphinx we do not find the least trace of the blistering prin- 

 ciple which so greatly distinguishes the Spanish fly. And this is 

 peculiar also to other species of Spanish flies, which however feed upon 

 very different plants, and in the most distinct climates. With respect 

 to the puncture of blood -sucking insects, everybody knows the differ- 

 ence of its effects from different insects. The puncture of the bed bug 

 (Acanthia lectularia, Fab.) leaves behind it a small, whitish, projecting 

 swelling ; that of the flea a spot made red by the wound, but which is 

 not painful. The puncture of our water bugs is painful; for example, 

 the Notonectce, Naucoris, and Sigara, the pain of which must espe- 

 cially be attributed to the saliva which is inserted in the wound. This 

 is the case also in the puncture of the common gnat, for the mechanical 

 injury is too trifling to produce such sensible pain. How very different 

 however is the inflammation after the puncture of this creature than in 

 the before named insects. The difference in tropical insects is still 

 greater. St. Pierre, in his voyage to the Mauritius, relates an instance 

 of a bug whose puncture produced a swelling of the size of a pigeon's 

 egg, which lasted five days*. The large exotic Tabani also cause 

 severe inflammation by their punctures, as Kirby andSpence have shown 

 in an instance ; with us also the species of the genera Chrysops and 

 Hcematopota, of the family of the Tabani, make painful punctures. 

 The sting also of the smaller genera of Culices are sometimes very 

 painful, as that for instance of the notorious Simulite, particularly when 

 they attack man and animals in hosts ; by the multitude of their stings 

 they then set the skin in such an inflamed state that it produces severe 

 illness, which frequently terminates in death. The same may be said 

 of the mosquitos, which are small Culices that belong probably to the 

 same genus, and which between the tropics are complete pests by 

 reason of the intolerable itching produced by their punctures. The 

 anthrax, or pustula maligna, which has been occasionally observed to 

 arise after the puncture of an insect is scarcely to be considered as the 

 consequence of its mere puncture, but of a poisonous lymph that has 

 probably still adhered to the proboscis of such a fly, which immediately 

 before may have punctured a diseased animal. The puncture therefore 



* Kirby and Spcncc, Introduction, vol. i. p. 171. 



