34 DRAGON FLIES VS. MOSQUITOES. 



escaping from the apex of the hypopharvnx." This seems 

 to settle the opinion hazarded by Di-. Dimniock ^"^ when 

 he says that he believes, " without as yet being able to 

 give anatomical proof of it, that the hypopharynx of 

 Culex contains a duct that pours out its poisonous saliva." 

 We have copied such of the figures of these authors as 

 illustrate the discoveries made ; notes of explanation on the 

 page facing the plate make further mention unnecessary. 



It has been demonstrated in many instances that if the 

 female be allowed to fill her abdomen and allowed to fly 

 away unmolested, the eifect of the poison is very much 

 reduced; in some cases entirely so. It is the interrupted 

 performance which produces the greatest itching. This 

 seems to prove that, if allowed to finish her meal un- 

 disturbed, the mosquito will pump back the venemo sal- 

 ivary secretion, whereas a quick withdrawal of the tul)e 

 results in the consequent abandonment of this irritating 

 fluid to be a source of annoyance in the flesh. 



AYere our Culicid foes only occasional visitants we 

 would not be greatly occupied with a means for their 

 extermination ; it is their overpowering number which 

 •constitutes the chief terror. Aside from their rapidly 

 succeeding broods, their nonmigratory and hibernating 

 tendencies are especially calculated to keep up the enor- 

 mous numbers which Nature seems to regard as their full 

 quota. 



Commenting on the latter, Westwood ^"^ and Young ^^^ 

 call attention to the fact that various species of the mos- 

 quito tribe hibernate in houses. Our own experiments in 

 raising many thousands of these insects have resulted in 

 the presence at this writing of a large number of three 

 species of Culex in our cellar. 



