14 



SCIENCE. 



[N. S. Vol. XV. No. 366. 



they found in fresh water, even where 

 adults occurred in enormous quantities. 

 This was prettily illustrated on the Eliza- 

 bethport meadows, from which the cities of 

 Newark and Elizabeth get the greatest pro- 

 portion of their mosquito siipply during the 

 summer. A large portion of these meadows 

 is flooded during extra high tides, or dur- 

 ing storms ; a number of fresh water creeks 

 run through them and rapidly freshen these 

 salt-water-covered areas. This is especially 

 true during the latter part of the summer 

 after a period of moderate tides. A two 

 days' collecting trip by an assistant failed 

 to develop any larvae of sollicitans until the 

 shore edge of the meadows was reached, 

 where the puddles were distinctly salty. 

 Everywhere else, while there were plenty of 

 other larvae discoverable those of sollicitans 

 were entirely absent. After a heavy storm 

 causing an unusually high tide, which 

 flooded the meadows, collections M^ere again 

 made and now, as salty water was found 

 almost everywhei'e, there was no difficulty 

 in obtaining larvse of sollicitans. Every at- 

 tempt was made to secure sollicitans larvaa 

 from fresli Avater; but almost without suc- 

 cess, even where the insects occurred in 

 swarms. I feel no hesitation in claiming 

 that under natural conditions the larva of 

 this species is never found in fresh water; 

 iinless it is in a pool that was salty when 

 the eggs were laid and has been freshened 

 subsequently by rains, or otherwise. 



Another fact was established by observa- 

 tions made during the summer : that is, the 

 species will travel long distances from its 

 breeding places. For miles throughout 

 South Jersey the only species of mosquito 

 found in any numbers is Culex sollicitans. 

 On the cranberry bogs on which I spent 

 some time countless thousands of these in- 

 sects occurred. The breeding conditions 

 for mosquito larvae were almost ideal and 

 plenty of larvae were found, but none were 

 of this species. All the specimens observed 



were females; males apparently do not go 

 away from their natural breeding places. 

 Twenty miles back from the coast, sollici- 

 tans is the dominant species and occurs 

 most of the summer. Forty miles from the 

 coast occasional flights occur; but their 

 period is short, rarely lasting more than a 

 week or ten days, and there may not be 

 more than one or two of them during the 

 season. From observations made and in- 

 formation gathered along shore and back 

 from it for some distance, it seems certain 

 that large swarms rise during favorable 

 evenings and are carried during the night 

 by the Avind for varying distances. The 

 direction is determined by the direction of 

 the wind, and may be as often out to sea as 

 inland. Swarms have been met with fifteen 

 miles from shore, and are common five 

 miles from shore. These are usually if not 

 always lost. This migration, if that term 

 can be properly employed, is contrary to 

 previous beliefs, my own included, and is 

 an important factor in the question of the 

 control of mosquitoes in the State. It takes 

 it out of the rank of local problems and 

 makes it a State affair. It is quite obvious 

 that no methods adopted at a point where 

 these mosquitoes do not breed can prevent 

 their abundance when the wind is in the 

 right direction to bring swarms of them 

 from the sea coast. On the other hand, 

 there seems to be no very great difficulty in 

 deciding upon the character of the work 

 that should be done to destroy the breeding 

 places of these pests. The measures are 

 largely of a permanent character. They 

 consist partly of draining, partly of ditch- 

 ing and partly of opening ways for the free 

 entrance of tides, and with them of certain 

 species of small fish that feed on mos- 

 quito larvae. At a comparatively small ex- 

 pense considerable areas can sometimes be 

 freed of breeding places. Much has been 

 done by private enterprise at seashore re- 

 sorts and there will be no difficulty in se- 



