166 MOSQUITOES OF NORTH AMERICA 



experienced an entomologist as Doctor P. E. Uhler, of Baltimore, appears in 

 the following letter from Doctor Uhler to Doctor Lambom, written in 1889, 

 just before the prizes were offered : 



" Permit me to say that you have taken hold of one of the hobbies of my 

 young manhood, in which I have never ceased to take an interest, and that is 

 the development of the Odonata in our rivers and marsh ditches to such an ex- 

 tent as to greatly reduce the number of mosquito larvae, as well as those of other 

 pestiferous Diptera which develop in such places. 



" How extensively this can be done I do not know; but as I have raised all the 

 common fonns of our Atlantic coastal plain region, I know that the dragon fly 

 larvae can be reared in vast numbers. 



" Of course, you know that each locality supports its own species, and the 

 forms which develop in the brackish drains and pools near tide, where they are 

 covered twice each day by salt water, cannot flourish in fresh water. Accord- 

 ingly, for the littoral belt from Long Island to Beaufort, N. C, I would select 

 Diplax berenice, Libellula auripennis, and Mezothemis longipennis. For the 

 region next inland from this, multitudes of common species could be had, such 

 as Anax Junius, ^schna heros, Libellula pulehella, L. luctuosa, L. semifasciata, 

 Plathemis trimaculata, and most of the species of Diplax. In the clear streams 

 which rush down from the hills, Cordulia, Epitheca, and Gomphus prevail. In 

 order to raise any of the species, Cyprinodonts and all other carnivorous fishes 

 will have to be excluded. 



" I agree with you that the mosquito nuisance might be greatly lessened by 

 filling the mosquito breeding waters with the larvte of dragon flies. 



" I believe this might be done by securing vast numbers of the eggs of dragon 

 flies, protecting them until hatched, and then turning them loose in the waters 

 where the mosquitoes breed most abundantly. 



" Along the seacoast, however, most of the eggs and hibernating female mos- 

 quitoes might be exterminated by burning the grass, in early cold weather of 

 autumn, all over the marshes. 



" Permit me to say that I hope you will offer the prize, as stated in your letter, 

 and agitate the subject quite extensively." 



The letter is also of interest as indicating Doctor Uhler's idea as to the most 

 valuable species. 



The three prizes were awarded to Mrs. Carrie B. Aaron, of Philadelphia; Mr. 

 A. C. Weeks, of Brooklyn ; and Mr. William Beutenmiiller, of New York City ; 

 and were jointly published in a volume entitled " Dragon Flies vs. Mosquitoes " 

 (ISTew York, 1890) . The essays were all admirable and brought together a great 

 deal of useful information on the subject of mosquitoes and mosquito enemies ; 

 but they did not solve the problem of the commercial breeding of dragon flies 

 for the destruction of mosquitoes. 



In the course of these essays, no doubts were expressed as to the value of 

 dragon flies as natural enemies of mosquitoes, and in fact Mr. Beutenmiiller 

 quoted from an army correspondent a rather striking statement of observations 

 indicating their effectiveness. But Doctor John B. Smith concludes from his 

 observations that, not only do the adult dragon flies fail to lessen materially the 

 mosquito supply, but that the dragon-fly larvte are as little entitled to credit for 

 effective work as are the adults. He points out that they are bottom feeders as 

 a rule, and usually below the range of " culex," while Anopheles is in no danger 



