The specimens taken on this migration proved on determination to belong to two species. A single one of Aedes sollicitans was captured on July 4. The other three, as well as the 21 taken on July 5, were of the species Aede8 niger. A. sollicitans and A.tceniorhynchua (a species closely allied to A. niger) have become noted for their migratory habits through the researches of Dr. Smith, of New Jersey. Breeding in the salt marshes along the seashore each summer develops immense swarms which spread inland to harass the inhabitants of cities even 30 miles away. In New Jersey A. sollicitans with A. cantator is the dominant species, tteniorhynchus being much less important, according to Dr. Smith : "Culex terniorhynchus develops with cantator and sollicitans under the same conditions and migrates with them; but it does not fly so far and is always so much less abundant that it needs no special account here." In the south, however, A. niger appears to be the dominant species and certainly flies, or is carried by winds, over the sea for long distances.
Late in the afternoon of July 5 the wind at Rebecca Shoal began to shift eastward, being east-northeast at 5 p. m. and east by north at blowing freshly. The last mosquito was taken at 8 p. m. Day light of July 6 still found the wind east by north and moderate. Two mosquitoes were captured, one at 5 a. m. and the second at 8h27 a. m., the last for the day. These individuals were, no doubt, the rear guard of those brought from Florida by the winds of the day pre ceding.
No more mosquitoes appeared until July 8, when 4 were taken during the forenoon; July 9 yielded 6 more, all Aides niger. Since the wind on July 7-8 and forenoon of July 9 was east—that is, it was blowing directly along the reef from Marquesas to Rebecca Shoal—the infer ence is that the mosquitoes were carried by the light breeze from these islands 24 miles away. Although there are extensive brackish swamps on the Marquesas Keys, it was found, when we visited them on July 30, that most of the water had evaporated, leaving only heavy mud. Rains had been infrequent during the preceding weeks with the result that swamps, which during the rainy season give rise to multi tudes of mosquitoes, were during July unproductive. There were many adult Aides niger in the grass and among the mangrove trees, however, and it was no doubt from their ranks that the few brought on east winds to Rebecca Shoal were derived.
It was hoped that another north wind would arise, so that the striking migration observed on July 4 and 5 might be duplicated. While this did not happen, I was fortunate enough to be on the station during a period of southerly breezes which brought an even more marked flight of mosquitoes. After several hours of calm on July
10, southeast squalls blew up late in the evening, lasting for two hours. The wind then veered into the south and finally held west-southwest, blowing freshly all night. At 5h30m a. m. of July 11 the first mosquito was captured; 32 more were added to the collection during the day, and were well distributed as to time, 2 being caught at a. m. and 1 at each of the following: 8h52m, 8h56m, 8h57m, 9h07'n, 9h08m, 9h16m, lOhllm, 11h38m, 11h40m, 12h05m, 12h10m, 12h15m, 1h20m, 1h22m, 1h25m, 3h30m, and between 6h30m and p. m. 7 more were taken, but none was noted after darkness fell.
The greater number rose only to the platform level, but 8 reached the second story above, and 1 was caught by one of the assistant keepers while painting the railing above the lantern at the very top of the sta tion, 65 feet above the water. In order to determine whether the insects were numerous just above the surface of the sea, I stationed myself on the boat-landing 8 feet from the water. One or two speci mens were caught here attempting to bite, but they seemed no more abundant than at the level of the platform 30 feet above.
During the night of July 11-12 the wind veered again toward the east; at 5 a. m. July 12 it was blowing freshly from east-southeast; 7 mosquitoes appeared between 9 a. m. and 2h20m p. m.
Judging from the direction of the wind previous to and during this migration of July 11 and 12, we conclude that these mosquitoes were carried from the shores of Cuba. The time required for the passage was apparently less than in the earlier migration from Florida; at the end of only 10 hours after the wind, as noted at Rebecca Shoal, began to blow from the southeast-8 p. m. to 5h30z° the following the first mosquito appeared, whereas in the first case 27 hours were required. Since the strength of the wind was similar in the two cases this disparity in the time intervals may indicate that, while the second flight may have left the Cuban coast at the point nearest to Rebecca Shoal-95 miles directly south—the first swarm probably took its departure far up the west coast of Florida; for the nearest point, Cape Sable, is only 105 miles from Rebecca.
The fact that the great majority of mosquitoes taken belong to the single species Aedes niger is evidence of its wide distribution and common occurrence in the south. Furthermore, this distribution is doubtless the result of the ability of these insects to sustain selves in the air and so to be carried long distances across the sea by winds. Howard, Dyar, and Knab give the range of this species as the Antilles and Florida from Tampa southward.