198 Papers from the Department of Marine Biology. 



undertaken by the three species, Aedes sollicitans, A. cantator, and A. 

 tceniorhynchus. Breeding only in the salt marshes along the seashore, 

 swarms of these three species migrate inland for distances of more than 

 30 miles; although capable of making these flights in calm weather, 

 favorable sea breezes were found to hasten them. 



As stated above, Dr. Mayer and others have noted in previous 

 years that mosquitoes were abundant on Loggerhead Key only after 

 the wind had been blowing from a certain quarter, usually the north- 

 east or north, for a considerable period. Furthermore, a change of 

 the wind into the east or west was always followed by a marked falling 

 off in the numbers of mosquitoes encountered about the laboratory. 

 The inference was that the northerly wind had blown large swarms of 

 the insects away from the west coast of Florida and that part of them 

 had reached Tortugas. If this inference were correct, even a small 

 building, such as the Rebecca Shoal light-station, lying out in the ocean 

 18 miles east of Loggerhead, should form a sufficiently large support to 

 attract a few mosquitoes which might be carried into its immediate 

 vicinity. Even during a wind of such strength that the insects could 

 not retain a foothold upon the windward side of the station, they would 

 be able to do so under its lee. 



OPPORTUNITIES FOR BREEDING OF MOSQUITOES AT 



REBECCA SHOAL. 



Obviously, in order to draw correct conclusions concerning the 

 occurrence of mosquitoes and flies at an isolated point, it is essential 

 that breeding-places there be under control. It was found that the 

 only fresh water available to mosquitoes at the Rebecca Shoal light- 

 station was contained in three sorts of receptacles ; first, the four tanks 

 on the lower floor for the storage of water obtained by draining through 

 iron spouts the rain-water falling on the slate roof; second, the small 

 depressions formed in the angles of the iron frame understructure; and 

 third, the bilge-water contained in the two boats suspended from davits. 



Concerning the small pockets and crevices in the steel frame of the 

 structure, it is only necessary to state that all water which lodged 

 therein was entirely evaporated by the sun in less time than would be 

 required merely for the hatching of mosquito eggs. Since rains were 

 infrequent in the period during which these observations were made, 

 the possibility of a replenishment was precluded. It is conceivable 

 that in a period of daily rainfall eggs deposited by mosquitoes in these 

 depressions might develop and by good fortune yield a few adults. Still 

 the rapid overflow during the characteristically heavy showers would 

 doubtless wash out most, if not all, eggs and larvae had they been present. 



The storage tanks were accessible to mosquitoes since their covers 

 did not fit closely; therefore it was necessary to be certain that no 

 larvae were present. Careful examination of the surface of the water 



