62 PREVENTIVE AKD REMEDIAL WORK AGAINST MOSQUITOES. 



the market gardeners in that vicinity preferred to get their supplies 

 from this source. 



Doctor Smith points out that there are many hundreds of acres 

 along the shores of Barnegat Bay, and especially along its upper por- 

 tion, where a very small amount of diking will serve to keep out salt 

 water and fit the land for certain truck crops. He also shows that 

 along a large portion of the Barnegat Bay line cranberry plants grow 

 annually to the very edge of the salt-marsh line, but that these could 

 not be improved because there was no way out across the marsh for 

 surface water. With the ditching going on, this land will become 

 available in large part at least and will allow the owners to derive a 

 revenue from land which is at present practically nonproductive. 

 Of course taxes will then be raised and the income of the townships 

 in which this land lies will be increased. 



THE PRACTICAL USE OF NATURAL ENEMIES OF MOSQUITOES. 

 SALAMANDERS, DRAGONFLIES, PREDACEOUS MOSQUITOES, AND FISH. 



Almost no practical use has been made artificially of the natural 

 enemies of mosquitoes except with fish. It is true that about 1898 

 Mr. Albert Koebele imported from California into Hawaii a large num- 

 ber of western salamanders {Diemydylus tortosus Esch.), which were 

 liberated in the upper part of the Makiki stream in the hope of redu- 

 cing the large number of mosquitoes breeding in small pools and in the 

 taro fields. He kept two of these salamanders for several weeks in 

 an open tank and they devoured all mosquito larvae that occurred 

 there; and while hundreds of the newly hatched mosquito larvae 

 could always be observed, none of them ever reached full growth. 

 Whether these salamanders have increased in Hawaii and at present 

 form an important element in the mosquito environment is not 

 recorded. 



Among the predatory insects it has been frequently suggestea that 

 dragonfiies are such important mosquito enemies that efforts should 

 be made to devise some artificial means of encouraging their increase, 

 and in fact the late Dr. R. H. Lamborn, of New York and Philadelphia, 

 offered a series of prizes for the three best essaj^s regarding the methods 

 of destroying mosquitoes and house flies, especially designating the 

 dragonfly for careful investigation. The prizes were awarded to Mrs. 

 Carrie B. Aaron, of Philadelphia, and Mr. A. C. Weeks and Mr. Wm. 

 Beutenmueller, both of New York, but none of the essayists was able 

 to solve the problem of the practical breeding on a large scale of 

 dragonfiies for mosquito extermination. 



It has been proposed to breed mosquitoes of the genera Psorophora 

 and Megarhinus, the larvae of which are extremely active and feed 

 so voraciously upon the larvae of other mosquitoes, but Psorophora 



