Butterflies and Moths. 405 
face to face, even but for a moment, with its exquisite beauty, which is 
much more enhanced and appreciated when seen in connection with the 
manifold and diversified surroundings of the wide outdoor world than 
in the tame and narrow confines of an ordinary museum show-case. 
Some butterflies have a way of assembling at times in little flocks, 
when they may go through a series of beautiful aérial evolutions. 
Species of Heliconius act in this manner, and there is hardly a more 
pleasing spectacle than that of a number of one or more of the more 
showy species of this genus dancing in the sunlight in the openings at 
or near the tops of forest trees. With charming grace they move in and 
out among themselves. Living fairy kites would be a suitable epithet 
for them then. 
The powers of flight of certain butterflies and moths are such as to 
enable them to cross fairly wide stretches of water. In July my duties 
took me down to the Essequebo coast. On the way to Suddie I observed 
thousands of Callidryas eubule, our yellow butterfly, flying across the 
Essequebo river from W akenaam to Hog Island and Great Troolie 
Island. They were flying chiefly in one’s, but two's, three’s, and higher 
numbers were not infrequent, while once in a way a flock of twelve to 
twenty could be counted. The great majority were males. A few 
were flyine in the opposite direction, or they had turmed back, as 
though afraid to make the flight or had ¢ hanged their minds. The 
insects looked much like bits of yellow paper being blown helter-skelter 
by wind, or like yellow flower petals streaming off from tall trees. 
Many of them pitched across the decks of the steamer. Soon after 
Kurubaru Islands were passed the butterfliés were to be seen flying 
from the mainland towards Wakenaam. Going on towards Aurora and 
Suddie, they were seen flying up stream, following, it seemed, more or 
less, the direction of the wind. The captain informed me that such 
flights occurred only at certain seasons, and that a couple of weeks before 
the butterflies were so plentiful crossing the river at Bartica that it 
looked like snow falling. This, I expect, was another butterfly—a 
Eurema probably. 
It is well known that Callidryas eubule migrates in countless 
myriads. One of these migratory swarms was observed by Sir Robert 
Schomburgk on the 18th of October, 1838, when going up the Esse- 
quebo River, and it continued crossing the course of the river for nine 
hours and a half, during which time his boat had ascended nine miles. A 
thousand million is not too high an estimate for the number of individ- 
uals in the swarm. The caterpillars feed on various species of Cassia, 
and many a Cassia must have been stripped of its leaves in the 
turning out of such a swarm. Some years ago Mr. Rodway, Curator 
of the Museum, on one of his orchid expeditions up the Demerara 
River, was also fortunate enough to witness a flying swarm of 
these pretty butterflies. The origin, destination, and cause of 
such migratory swarms are, | believe, still matters of speculation. 
