80 DRAGON FLIES VS. MOSQUITOES, 



bottom, a swarm of gnats, and a vertical sun. The insects 

 were confined in this way for several days, until many of 

 the flies and dragon flies perished, and out of feelings of 

 compassion the survivors were allowed to escape. Fre- 

 quent and prolonged visits during the period of confine- 

 ment failed to show any attem])ts to oviposit, and a care- 

 ful scrutiny of the water plants failed to show a single 

 egg. The following week a pair of Anax Junius in 

 copulo and several single specimens were captured, and 

 placed in the rooms with a number of fresh flies, with 

 the same lack of success ; and again in September, with a 

 similar result. 



III. Habits of Dragon Flies limited to Scope of 

 Object to be Accomplished. 



The most important results to be attained in the rearing 

 of any insect is the fertilization and deposition of ova. 

 With this paper in view, during the month of August, in 

 addition to the foregoing experiments, I visited a number 

 of small ponds, marshy pools, and other places frequented 

 by these insects, to ascertain if possible the necessary con- 

 ditions under which these acts occur, with the following 

 result : The greatest activity was developed under a verti- 

 cal sun, in a quiet atmosphere; a fair breeze slightly di- 

 minished this, a strong breeze greatly reduced it, while the 

 passage of a cloud over the sun with a cool breeze brought 

 it to a minimum. The insects do not take flight at an 

 early hour, and, with the exception of Anax junius~aiid 

 ^shna constricta and heros, cease from flight as the sun 

 approaches the horizon. A solitary specimen of one of the 

 three species above named may be occasionally observed 



