DinECT INJURIES CAUSED BY INSECTS. 113 



and thus glutted itself with the l)lood of man. — In tra- 

 velling- between Edam and Purmerend in North Hol- 

 land (July 21, 1815), in an open vehicle, I was much 

 teased by another bird-fly (Ormihom?/ia avicularia, 

 Latr.) (two individuals of which I caught) alighting 

 upon my head, and inserting its rostrum into my flesh. 

 — Mr. Sheppard remarks, as a reason for this derelic- 

 tion of their appropriate food, that no sooner does life 

 depart from the bird that these flies infest, than they 

 immediately desert it and take flight, alighting upon 

 the first living creature that they meet with ; which if 

 it be not a bird they soon quit, but, as it should seem 

 from the above facts, not before they have made a trial 

 how it will suit them as food. 



But of all the insect-tormentors of man, none are so 

 loudly and universally complained of as the species of 

 the genus Culex, L., Avhether known by the name of 

 gnats or mosquitos. Pliny, after Aristotle, distin- 

 guishes well between Hi/menoptera and Diplera, when 

 he says the former have their sting in their tail, and the 

 latter in their mouth ; and that to the one this weapon 

 is given as the instrument of vengeance, and to the 

 other of avidity''. But the instrument of avidity in the 

 genus of which I am speaking, is even more terrible 

 than that of vengeance in most insects that are armed 

 with it : like the latter also, as appears from the con- 

 sequent inflammation and tumour, it instills into its 

 wound a poison ; the principal use of which, however, 

 is to render the blood more fluid and fitter for suction. 

 This weapon, which is more complex than the sting of 

 hymenopterous insects, consisting of five pieces besides 

 the exterior sheath, some of which seem simply lan- 



" Plin. Ilist. Nat. 1. xi. c. 28. Aristot. Hist. Animal. 1. i. c. 5. 

 VOL. I. I 



