DRAGON FLIES AND MOSQUITOES 165 



he asserts that " no Anopheles larva has a chance in any bit of water inhabited 

 by them. . . , Their surface habit and their tendency to get near the edges 

 make them especially dangerous to Anopheles larvae, which absolutely fail to 

 maintain themselves within the range of these beetles." The larvae of the 

 Gyrinidae are also predaceous but live at the bottom and no observations of their 

 preying upon mosquito larvjE have come to hand. 



Dr. Eysell dwells upon the efficiency of aquatic Hemiptera as mosquito de- 

 stroyers. He states that of the forms living beneath the water Nepa, Ranatra, 

 Naiicoris, Notonecta and Corixa destroy great numbers of mosquito larvae. The 

 forms living upon the water-surface, like Limnohates and Hydrometra, destroy 

 emerging images or females in the act of depositing eggs. 



In German New Guinea, Drs. Dempwolff and Wendland, in the course of 

 their malaria work, found that waters which contained many Notonecta har- 

 bored no mosquito larvae. This led them to introduce these insects into the 17 

 water-tanks of an European settlement with the result that within a week the 

 mosquito larvae had all disappeared from the tanks and the number of mosquitoes 

 inside the houses was considerably diminished. Further experiments with 

 Notonecta, initiated with mosquito-breeding pools, gave no practical results on 

 account of the rapid drying up of the pools. 



Doctor Smith also gives observations upon several aquatic bugs, indicating 

 that Notonecta, Nepa, and Ranatra are effective enemies of mosquito larvae but 

 that, owing to the fact that they occur chiefly in permanent waters, their use- 

 fulness is restricted. He quotes an interesting observation by Mr. Yiereck, as 

 follows : 



" The early stages of Ranatra fusca were destructive to wrigglers. With 

 their raptorial legs they nip the larva near the breathing tube, then either drop 

 or suck it. Quite a number were nipped and dropped, and, once dropped, they 

 rose no more. Pupae, both of Anopheles and Culex, were expert in evading the 

 grasp and were not readily caught. In less than an hour three Ranatra killed 

 and sucked ninety-eight larvae. It is a question whether Ranatra would be use- 

 ful in stagnant pools, because the specimens used in the experiment could only 

 be found in the clear water of a lily pond where, no doubt, they controlled the 

 Anopheles; but when put into the stagnant water which sollicitans inhabits, 

 they died." 



Dragon flies feed upon flying mosquitoes, and their larvae feed upon mosquito 

 larvae and pupae. This propensity of dragon flies is so well known that in some 

 sections of the country they are popularly termed mosquito hawks. The late 

 Dr. E. H. Lamborn, of New York City, was so impressed with the voracity of 

 dragon flies, from observations made while engaged in railroad building in the 

 swampy forests around the head of Lake Superior, that, in 1889, he offered three 

 prizes for the best essays on the mosquito and the house fly. These essays were 

 to include observations and original investigations regarding methods of de- 

 stroying the mosquito and the house fly, observations and experiments to best 

 accomplish the artificial multiplication of dragon flies to breed them in large 

 numbers, and to include an estimate of the cost of producing them by the 

 thousand. How feasible his plan seemed, not only to himself, but even to as 



