IX 
WARNING COLORATION AND MIMICRY 
239 
of protection. Another exceptional case is that of the very 
conspicuous caterpillar of the spurge hawk-moth (Deilephila 
euphorbise), which was at once eaten by a lizard, although, as 
it exjmses itself on its food-plant in the daytime and is very 
abundant in some localities, it must almost certainly be disliked 
by birds or by some animals who would otherwise devour it. 
If disturbed while feeding it is said to turn round with fury 
and eject a quantity of green liquid, of an acid and disagree¬ 
able smell similar to that of the spurge milk, only worse. 1 
These facts, and Mr. Poulton’s evidence that some larvae 
rejected by lizards at first will be eaten if the lizards are very 
hungry, show that there are differences in the amount of the 
distastefulness, and render it probable that if other food were 
wanting many of these conspicuous insects would be eaten. 
It is the abundance of the eatable kinds that gives value to 
the inedibility of the smaller number ; and this is probably 
the reason why so many insects rely on protective colouring 
rather than on the acquisition of any kind of defensive 
weapons. In the long run the powers of attack and defence 
must balance each other. Hence we see that even the power¬ 
ful stings of bees and wasps only protect them against some 
enemies, since a tribe of birds, the bee-eaters, have been 
developed which feed upon them, and some frogs and lizards 
do so occasionally. 
The preceding outline will sufficiently explain the character¬ 
istics of “ warning coloration ” and the end it serves in nature. 
There are many other curious modifications of it, but these will 
be best appreciated after we have discussed the remarkable 
phenomenon of “mimicry,” which is bound up with and 
altogether depends upon “ warning colour,” and is in some 
cases the chief indication we have of the possession of some 
offensive weapon to secure the safety of the species imitated. 
Mimicry. 
This term has been given to a form of protective resem¬ 
blance, in which one species so closely resembles another in 
external form and colouring as to be mistaken for it, although 
the two may not be really allied and often belong to distinct 
1 Stainton’s Manual of Butterflies and Moths, vol. i. p. 93 ; E. B. 
Poulton, Proceedings of the Zool. Soc. of London, 1887, pp. 191-274. 
