MOSQUITO BIOLOGY 49 



extermination in the long run than any other possible method. Mr. 

 Viereck's experiments also prove, what I suspected as the result of my 

 own observations ; that a certain percentage of the eggs laid did not 

 hatch when first covered with water. This is a provision of nature for 

 the continuance of the species ; that in case of a covering too slight to 

 bring the brood to maturity, there should be a remnant lying over until 

 a later period, ready to hatch at the second or third covering, or until 

 the spring following. In other words, the evidence tends to show that 

 out of say 200 eggs laid by an individual, 100 would hatch the first time 

 they were covered with water provided the eggs had been uncovered for 

 at least twenty-four hours. Of the remainder, fifty would probably 

 hatch at the second covering and of the balance, ten would lie over until 

 the season following, while the others would hatch if covered during the 

 season. Assuming however that of the 200 eggs from an individual of 

 the first brood, none was covered by water during the summer for a 

 long enough time to produce the larva, the indications are that at least 

 fifty per cent would lie over safely until the season following, ready to 

 take advantage of spring conditions. 



As for the points selected for oviposition by the females, that includes 

 practically every damp place on the salt marsh and the country immedi- 

 ately adjacent thereto. For example, a cornfield noted by Mr. Viereck 

 came down to a corner edging on the marsh, and while it was plowed 

 and planted like the rest, a pool which formed in that marsh corner 

 contained soUicitans larvae while none were found in apparently much 

 more attractive places away from the direct salt marsh influence. Where 

 a shore town has been laid out with streets and avenues running in all 

 directions through a salt area, the depressions between the streets re- 

 tain their salt character and will breed soUicitans whenever water 

 gathers, though they may be dry from June 1 to December 1. I have in 

 mind several places of this kind which become water covered in winter 

 only, remain water covered until late in May or early in June and ma- 

 ture a brood composed of practically all the eggs that were laid on 

 that place during the preceding season. There is no water from June 1 

 or thereabouts until frost; but mosquitoes are always there and eggs 

 are laid freely. 



On the other hand, once out of the immediate influence of the marsh, 

 neither eggs nor larvae are found, no matter how abundant the adults 

 may be. This is a point which I have tested and had tested again and 

 again, every one of my assistants having collected within the range of 

 soUicitans from the salt marsh to the inland, and all having had exactly 

 the same results, whether they collected blindly on definite instructions, 



