xxxiv Proceedings of the South African Philosophical Society. 
combined with warning colour; in spite of which, however, these 
insects are easily scared by the presence of an intruder, and rapidly 
take to flight. | 
In the Order Diptera (or two-winged Flies) the colouration for 
adaptation to surroundings does not play a very important rdéle so 
far as the South African species are concerned. In the genus Bom- 
bylius, however, the body of which is clothed with long white or 
pale yellowish hairs, and whose wings are either transparent or veined 
with a slightly fuscous or brown tinge, the South African forms, 
Bombylius serviller, B. stylucorms, B. argentifer, Systoecus rubricosus, 
.&¢c., harmonise wonderfully with the soil on which they stand while 
in the act of depositing their egg or eggs beside those of other 
insects. on which the young will eventually prey. The species with 
lighter, almost white, hairs are only met with on whitish sandy 
patches or spots. They can be observed along the seashore or not 
far inland, from Salt River to Namaqualand. 
From the Flies we pass to the Butterflies and Moths (LEptr- 
DOPTERA). This is par excellence the Order in which, throughout all 
the stages of growth of the insect, protective colours are in the 
ascendant. The brilliant colours with which most of the diurnal 
butterflies are adorned are, of course, well known. But what is 
perhaps not so well known is that of the 415 species occurring in 
South Africa only 22 can be said to have the under side of the 
wings brighter or more conspicuously coloured than the upper. 
The very large proportion of butterflies with a more dingy or less 
-conspicuously coloured under side, is explained by the fact that most 
of them when at rest or in their hiding-place have the wings folded, 
and the under side of the wings only is exposed to view. Were the 
under side adorned with bright colours the presence of the insect 
would be immediately detected, and it would fall so much more 
easily a prey to its enemies. To assume, however, that those 
species, the under side of whose wings 1s more conspicuous or 
more brilliantly coloured than the upper side, would be more 
easily preyed upon on account of their detection being made easier 
would be a mistake, as will be seen later on, because this very 
brilliant pattern contributes in many cases to the concealment of the 
insect by producing an illusion. 
In a series of the ‘“ Brown” (Melanitis leda), which frequents 
underwood, and the upper side of the wings of which is modestly 
coloured, we find on the under side a series of dull tints, infinitely 
variable yet harmonising constantly with the tints of the environ- 
ment. Charaxes varanes, which is probably the handsomest butterfly 
found in the Cape Colony, and almost excels Melamtis leda in the 
