1933] Migratory Flight of Catopsilia eubule 133 
hereabouts during this migration included Colias eury- 
theme Bdv., Zerene caesonia Stoll, and Junonia coenia Hbn., 
but they showed no disposition to join eubule in its south- 
ward flight. 
Discussing the migration of butterflies, Clark C32) sug- 
gests that the aggregation of male pierids about puddles of 
water is evidence of overcrowding, such assemblages being 
composed of the weaker individuals that have been unable 
to secure food because of competition and persecution by 
their more vigorous fellows ; they therefore gather on 
muddy areas to obtain water. They subsequently begin to 
wander, and this leads to the formation of large migrating 
swarms which are almost wholly composed of males. They 
usually fly against the wind. He considers the migrations 
of C. eubule to be of this type, and that they therefore rep- 
resent the end of the natural process of the elimination of 
surplus males. This explanation does not fit the facts in 
the present instance. During 1932 very few assemblages of 
pierids in muddy spots were seen in the region where the 
flight took place, although they were exceedingly numerous 
in 1931. This suggests that the heat and drought of 1931 
brought them together at wet places, and that overcrowd- 
ing had little to do with this phenomenon. Furthermore, 
these aggregations consisted mostly of Eurema lisa Bdv. & 
LeC., with some Colias , but only one or two eubul# were 
ever seen in any one such group. In the migration observed 
in 1932, many females were seen. There was no tendency 
to fly against the wind; on the contrary, their flight was 
independent of wind direction. 
There is good reason to believe that migration southward 
is an annual event in the life of this species in many parts 
of the United States. Scudder (’99) refers to it as a fre- 
quent migrant in the eastern states, and Brower (’30) says 
that in the neighborhood of Willard, Missouri, it “migrates 
through August, September, and October, coming from the 
northwest/’ Williams (’30-a) has collected many records 
of migration in the genus Catopsilia ; many of these refer 
to C. florella Fab. in South Africa, and C. eubule and C. 
statira Cram, in tropical America. Most of the published 
records of “Catopsilia sp.” or of “yellow butterflies” prob- 
ably belong to these three species. In another paper Wil- 
