Nature's Night Lights. 171 



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 Batra- 

 chians, reptiles, &c.) are unpalatable to the rapa- 

 cious 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 



