II ANIMAL LIFE IN THE TROPICAL FORESTS 275 
machia trochilus and colubris) literally swarmed on the sands, 
their glittering wings lying wide open on the flat surface.” } 
When we consider that only sixty-four species of butter- 
flies have been found in Britain and about 150 in Germany, 
many of which are very rare and local, so that these numbers 
are the result of the work of hundreds of collectors for a long 
series of years, we see at once the immense wealth of the 
equatorial zone in this form of life. 
Peculiar Habits of Tropical Butterflies 
The habits of the butterflies of the tropics offer many curious 
points rarely or never observed among those of the temperate 
zone. The majority, as with us, are truly diurnal, but there 
are some Eastern Morphide and the entire American family 
Brassolide, which are crecuspular, coming out after sunset 
and flitting about the roads till it is nearly dark. Others, 
though flying in the daytime, are only found in the gloomiest 
recesses of the forest, where a constant twilight may be said 
to prevail. The majority of the species fly at a moderate 
height (from five to ten feet above the ground), while a few 
usually keep higher up and are difficult to capture; but a 
large number, especially the Satyride, many Erycinide, and 
some few Nymphalide, keep always close to the ground and 
usually settle on or among the lowest herbage. As regards 
the mode of flight, the extensive and almost exclusively 
tropical families of Heliconide and Danaide fly very slowly, 
with a gentle undulating or floating motion which is almost 
peculiar to them. Many of the strong-bodied Nymphalide 
and Hesperide, on the other hand, have an excessively rapid 
flight, darting by so swiftly that the eye cannot follow them, 
and in some cases producing a deep sound louder than that of 
the humming-birds. 
The places they frequent, and their mode of resting, 
are various and often remarkable. A considerable number 
frequent damp open places, especially river-sides and the 
margins of pools, assembling together in flocks of hundreds of 
individuals ; but these are almost entirely composed of males, 
the females remaining in the forests, where, towards the after 
noon, their partners join them. The majority of butterflies 
1 The Naturalist on the River Amazons, 2d ed., p. 331. 
