CH. XVI.] DIPTEROUS INSECTS. 233 



seem to overthrow all our reasoning. The sound 

 increases (authors have written dissertations on the 

 question whether it is loudest on approaching or re- 

 ceding from the hearer), and a gnat, belonging to a 

 genus closely allied to the chironomus, after playing 

 a short time near the light, settles on our hand, and 

 commences its operation of working its sucker into 

 our fingers, although, for the purpose of witnessing 

 its mode of proceeding, we have advanced our hand 

 quite close to the light. 



Should this circumstance be put in opposition to 

 our former argument, we would merely observe, that 

 the habits, as well as the proceedings, of the two 

 insects, are so totally different, that a comparison 

 ought not to be made between them. 



CHAPTER XVI. 



THE NATURAL HISTORY OF VARIOUS OBNOXIOUS SPECIES OP 

 DIPTEROUS INSECTS CONTINUED. 



MoschetoThe Black Fly of America Domestic Fly The 

 Hungarian Fly Gadflies Breeseflies Structure of Mouth of 

 Tabanus and Gnat Females only bloodthirsty The Zimbr 

 The Forest-fly. 



IF it were merely for the purpose of showing to 

 mankind that insects are not such insignificant ob- 

 jects in the scale of creation as they have been as- 

 suredly considered by many persons, perhaps no 

 more available " argumentum ad hominem" could be 

 produced than that afforded by those species which 

 formed the subject of the last paragraph of the pre- 

 ceding chapter ; but there are many others, which, 

 from the severity of their attacks both upon man 

 and beast, seem fully competent to revenge the 

 U 2 



