Septembee 5, 1902.] 



SCIENCE. 



391 



over the relations of one discipline to another. 

 But this ought not to hinder any science from 

 setting its own limits and doing its own work, 

 while it accepts all the aid it can get from 

 others. No science is more widely indebted 

 than is psychology; but psychology demands, 

 no less than others — such is scientific selfish- 

 ness ! — that she be allowed to work out her own 

 ■destiny in her own way. 



I. Madison Bentley. 

 Cornell University. 



SHORTER ARTICLES. 



THE SALT MARSH MOSQUITO, CULEX SOLLICITANS 



WLK. 



In Science for January 3, 1902, p. 13, under 

 the caption 'Concerning Certain Mosquitoes' 

 I pointed out that Gulex sollicitans was the 

 dominant form throughout a large portion of 

 the State of New Jersey. Upon our ability to 

 control this species depended the riddance of 

 the State to any notable extent, and the life 

 cycle of the species became, therefore, a mat- 

 ter of the greatest importance. I suspected 

 even at that time that this species departed 

 materially from the stock history given for 

 Gulex and assumed for this species; but my 

 observations had been sufficient only to sug- 

 gest the need of closer study. I showed at 

 that time that, by breeding in salt water and 

 by migrating for long distances the species 

 had distinctive characters. And, bye-the-bye, 

 there is no more perniciously erroneous popu- 

 lar statement than that mosquitoes do not fly 

 far from the place they were bred. It is abso- 

 lutely untrue of most of the species and not 

 entirely true of any. The only case where 

 it is practically true is where a species is limit- 

 ed in its breeding places, e. g., the species that 

 breeds only in the leaves of the pitcher plant. 

 Of the salt marsh mosquito it is conspicuously 

 incorrect. 



In February and March I started a hunt 

 for the adults on the supposition that the 

 female hibernated. My assistant, Mr. Dicker- 

 son, searched every nook and cranny that 

 might shelter a mosquito in a seashore locality 

 where, during the summer, the insects had 

 driven out all guests. C'ulex pungens and 



Anopheles were found in numbers; but of 

 sollicitans not one ! I had no better luck 

 when I took up the search myself, and even a 

 reward offered to the natives for every speci- 

 men brought to nie, failed to produce returns. 

 I concluded, therefore, that the insects did 

 not winter in the adult stage and began a 

 hunt for larvae. I knew that Aedes smithii 

 wintered in the larval stage and that the wig- 

 glers would stand repeated freezings. But I 

 failed also to find larvae in the very regions 

 where they were abundant in 1901, and where 

 I had also seen them in 1900. 



A wintering in the egg stage was unknown 

 for Culex, but I was driven to that alternative 

 and watched carefully for ' signs.' They came 

 as the water warmed up. First, larvae were 

 found in pools high up which had been filled 

 by the winter tides. The temperature of the 

 water was distinctly higher than that of the 

 air in the morning and evening and several 

 degrees higher than that of sea water. Area 

 after area became populated and there were 

 millions of larvae, growing very slowly, before 

 a solitary mosquito was seen. A hibernation 

 in the egg stage seemed obvious; but I ran 

 against the fact that some of the areas swarm- 

 ing with larvse were dry during the sunmier 

 and fall of 1901 and became water-filled only 

 during the winter storms. If the eggs hiber- 

 nated on that ground they must have been 

 laid on dry soil or on the grasses ! This then 

 was the point to which I had arrived at the 

 opening of the breeding season. College 

 duties and other matters prevented a resump- 

 tion of the work until July 7, when Mr. 

 Dickerson and I spent a week at Five Mile 

 beach; I kept him in the field another week 

 alone and rejoined him when the experiments 

 were expected to produce results. Our out- 

 fit consisted of a series of seven tubs sunk 

 into the marsh so as to project only a little 

 above the level. In five of them was placed 

 sod from the marsh and two were left bare. 

 Sea water was placed in all save one of the 

 tubs in varying quantities. Two tubs were 

 left open — one with sod, one without; the 

 others were covered with mosquito netting. 

 Conditions along shore at this time were very 

 dry and breeding places were fast disappear- 



