288 
Psyche 
[Vol. 92 
found males swarming in early April 1981, and specific observations 
were made during the three following springs. I was at the study site 
each evening 30 min. prior to daily swarming. 
Male activity. Male swarming periods were monitored on 12 
days (1982 n = 9, 1983 n = 3). The start of swarming was noted when 
the first male was seen constructing a balloon at a swarming station 
and three more males were seen during the next minute. At the start 
of activity, light intensity was indexed by estimating the percent 
(nearest 10%) of the sky occluded by clouds. Temperature and wind 
speed at a height of 1 m were also taken. Activity period stopped 
when no males were found at swarming stations monitored that 
evening. All swarms of a given evening broke up within a 3 min. 
period. 
Swarm station, height, size. Each swarming station was marked 
with a numbered wooden stake put into the ground below the 
swarm. Height of swarms was measured to the nearest . 1 m with a 
2.5 m pole marked at .1 m intervals. Measurement was taken from 
ground level beneath swarms to swarm center. 
White balloons carried by males made them conspicuous and the 
number of males in a swarm (size of swarm) was estimated by 
counting balloons. Since females and possibly some males do not 
carry balloons, only displaying males were counted. Because of 
movement by males in swarms and difficulty in counting balloons, 
swarms with more than 10 males were estimated to the nearest 5 
males. 
Mating behavior. During swarming considerable effort was 
made to locate and watch pairs as they coupled and mated. As some 
pairs formed in the swarm they were collected. Uncoupled members 
of the swarm were also captured. The sizes of females, coupled 
males and uncoupled males were measured to investigate whether or 
not large males were more likely to mate with females. Size was 
determined by measuring with a ocular micrometer the lengths of a 
wing and hind femur of each individual. 
Results 
Both sexes were found on leaves near swarming stations 15-30 
min. prior to swarming activity. During this time males flew from 
leaf to leaf and walked along the leaf margins from the base to tip 
and then back again, possibly searching for females. 
