WARNING COLOURS AND MIMICRY 149 



hornet and a moth belong to widely distinct orders, and 

 have nothing whatever in common. What, therefore, can 

 be the meaning of the close superficial likeness which 

 exists between them ? At one time naturalists were quite 

 unable to answer this question. To-day, in the theory of 

 mimicry, we find a plausible explanation. Like the wasp, 

 the hornet is a protected species. Everyone knows that 

 it is capable of inflicting painful and even dangerous 

 wounds with its poison-injecting sting ; and as a warning 

 to its would-be assailants it displays a livery of yellow 

 and dark brown. Now it is not difficult to believe that 

 a perfectly harmless insect which happens to look like a 

 hornet may actually be mistaken for a hornet ; and in the 

 case of the poplar clearwing there is little doubt that this 

 really occurs. The moth shares in the evil reputation of 

 its model, being passed over as dangerous by insectivorous 

 creatures which would gladly eat it did they realise the 

 true state of affairs. We must not think, however, that 

 any conscious imitation is implied when one insect is said 

 to mimic another. No amount of effort on the part of a 

 moth would suffice to alter its appearance in the least 

 degree. But just as natural selection has clothed one set 

 of insects with warning liveries, so the same agency has 

 turned out another set of elaborate frauds. 



Bees, wasps, and their kindred furnish models for 

 mimicry in all parts of the world. The males of the 

 various stinging species are really mimics of their own 

 wives and daughters, for they have no stings, and their 

 warning liveries are thus lacking in direct significance. 

 Then there is a whole group of clear-winged moths which 

 look like hornets, wasps, and humble-bees. Many two- 

 winged flies also counterfeit these stinging insects. There 

 is one called Chrysotoams silvarum which looks exactly 

 like a wasp. Another species, known as Volucella bom- 



