152 
THE NATURALIST IN LA PLATA. 
July, 1892. 
conjectured, protects itself, or rather is involuntarily pro¬ 
tected, by means of its frequent flashing light. We are thus 
forced to the conclusion that, while the common house-fly 
and many other diurnal insects spend a considerable portion 
of the daylight in purely sportive exercises, the firefly, 
possessing in its light a protection from nocturnal enemies, 
puts off its pastimes until the evening; then, when its 
carnival of two or three hours’ duration is over, retires also 
to rest, putting out its candle, and so exposing itself to the 
dangers which surround other diurnal species during the 
hours of darkness. I have spoken of the firefly’s pastimes 
advisedly, for I have really never been able to detect it doing 
anything in the evening beyond flitting aimlessly about, like 
house-flies in a room, hovering and revolving in company by 
the hour, apparently for amusement. Thus, the more closely 
we look at the facts, the more unsatisfactory does the 
explanation seem. That the firefly should have become 
possessed of so elaborate a machinery, producing incidentally 
such splendid results, merely as a protection against one set 
of enemies for a portion only of the period during which they 
are active, is altogether incredible. 
“ The current theory, which we owe to Belt, is a prettier 
one. Certain insects (also certain Batracliians, reptiles, &c.), 
are unpalatable to the rapacious kinds; it is therefore a direct 
advantage to these unpalatable species to be distinguishable 
from all the persecuted, and the more conspicuous and well- 
known they are, the less likely are they to be mistaken by 
birds, insectivorous mammals, &c., for eatable kinds and 
caught or injured. Hence we find that many such species 
have acquired for their protection very brilliant or strongly- 
contrasted colours—warning colours—which insect-eaters 
come to know. 
“ The firefly, a soft-bodied, slow-flying insect, is easily 
caught and injured, but it is not fit for food, and, therefore, 
says the theory, lest it should be injured or killed by mistake, 
- it has a fiery spark to warn enemies — birds, bats, and 
rapacious insects—that it is uneatable. 
“ The theory of warning colours is an excellent one, but it 
has been pushed too far. We have seen that one of the most 
common fireflies is diurnal in habits, or, at any rate, that 
it performs all the important business of its life by day, when 
it has neither bright colour nor light to warn its bird enemies; 
and out of every hundred species of insect-eating birds 
at least ninety-nine are diurnal. Raptorial insects, as I have 
said, feed freely on fire-flies, so that the supposed warning is 
not for them, and it would be hard to believe that the 
magnificent display made by luminous insects is useful only 
