LIFE HISTORIES OF THE ODOXATA. 49 



tedious and varied existence wlieii, if ever, they are to do 

 the most effective work in thinning the Culicid ranks. 

 Enough has been written of the hours and habits of flight. 

 The season of their usefuhiess is for the most part re- 

 stricted to the warm weather. Thev become rarer about 

 the time that mosquitoes are the most obnoxious. 



In the matter of flight they are very local, seldom 

 stravino- from their accustomed haunts, save in case of 

 migration. To us it seems impossible to conceive that 

 they could ever be brought to frequent deep woods or city 

 streets ; yet these widely dissimilar localities are each fer- 

 tile breeding places for Culex. 



In their feeding habits the Odonats are very difficult to 

 watch. Our experiments and observations lead us to be- 

 lieve that they prefer robust, meaty insects, such as grass- 

 httppers and bugs. The study of their food preferences 

 in confinement is most misleading. So rapacious are they, 

 so fierce in disjiosition, and so well adapted for aiiy kind 

 of chewing, that they will eat anything which is forced 

 upon their notice. In one case an Anax Junius devoured 

 with evident relish seven of its own abdominal segments 

 which were severed from the rest of its body. 



The habit of migration among dragon flies will militate 

 against their efficiency as mosquito destroyers. This pe- 

 culiarity has drawn the attention of entomologists for 

 many years past. Newton, ^'^- Van Hasslet,^^^ Kuwert,^^ 

 Van Bemmelen,^^^ and Chvzer ^^ have all noted extensive 

 migrations in Sweden, Denmark, Tlie Hague, Rotterdam, 

 and Hungary; in one instance lasting four days. Ma- 

 thew,^^ Shaupp,^^^ and Froniont ^^ have observed migrat- 

 ing swarms at sea, far from land. Torrey^*"^ gives an 

 account of a flight at Weymouth, ]Massachusetts, extending 



