PSYCHE 
[Febniai'V 
irregular; single individuals would at times leave the swarm, and cutting a wide 
circle, return into it. Sometimes the.se stray individuals would fly for a short dis- 
tance with a ])eculiar rapid zigzag motion — a series of short sidewi.se jerks — and 
then return with the ordinary steady flight. In spite of these varied evolutions the 
mosquitoes showed a tendency to face in one direction, presumahly towards the 
wind, although the evening was perfectly calm and there was no breeze ai)])arent. 
As it began to darken the males began to leave the swarm one by one, flying upward, 
cither into surrounding trees or more often they would disajtpear. into the sky. On 
this evening copulaticm was not ob.served and from the following observations it 
may be assumed that union only takes place during the early j)art of the swarming. 
Although stormy and cold weather intervened, the following Sunday ]>roved 
fine and the ledge on the island was again visited. Shortly before .5 o’clock, with 
the sun still shining but near the horizon, a few males were found already a.ssembled 
and engaged in their circling flight above the grass-tufts. ( fthers came from dif- 
ferent directions and joinecl the swarm and by sunset it consisted of perhaps sixty 
or seventy moscpiitoes. It was difficult to follow the movements of .single mosqui- 
toes but it seemed that in circling about they described a figure-of-eight — some- 
times on a plane, or ascending and descending. At 5.15 a pair was seen falling 
out of the middle of the swarm, gra])])ling each other as they fell. They had not 
dropped far below the swarm when union was affected, and, swinging out in ojiposite 
directions, still united they drifteil slowly away towards the ground. Within ten 
minutes six pairs were seen to drop out of the swarm and co])ulate in this manner 
but after that no more. Three of the pairs were captured in the net; one pair rested 
in the bottom of the net about a minute, then separated and flew out; the other two 
])airs remained united even after death in the killing-bottle. It could not be deter- 
mined if in the slow flight of the united pair the female leads off as is the ca.se with 
pipienn, but it is to be presumed so, as she is the larger. Neither could it be posi- 
tively ascertained whether any females formed part of the swarm. None were seen 
to enter at the time copulation took place, but with the rapid and confused move- 
ments of the members of the swarm (some flying out of the swarm and back again, 
as described above) it was impo.ssible to keep all the individuals under close observa- 
tion. However it is safe to conclude that, as in pipiens, the swarm proper consists 
wholly of males — certainly the fifteen specimens captured out of the swarm on Oct. 
7 were all males. If there is any choice made in the selection of a mate it must be 
on the ])art of the female, for there appears to be no effort made, or any struggle, 
on the j)art of the males to secure the female entering the swarm. 
An intere.sting fact was the promjit reaction of the entire swarm to sound. The 
