THE BUTTERFLY'S WATERPROOF 



observations on the sleeping habits of small butter- 

 flies. I studied the small heath butterfly part of one 

 fine evening, and for an hour or two next day a 

 wringing wet morning. Every small heath that I 

 found in three different spots slept in just the same 

 way. Its wings were close folded so close as to 

 remind one of the thin leaves of a new book the 

 upper pair being laid well back, so that very little 

 showed above the lower pair. The brown patch and 

 the black eye, which are quite noticeable on the 

 under sides of these upper wings when the butterfly 

 is resting in the sunshine, were not to be seen. The 

 common blues in sleep laid back their upper wings 

 exactly the same way. But there was a marked 

 difference between the position in sleep of heath and 

 of blue. The blues slept along the stem of grass 

 head sometimes upward, more often downward ; the 

 heath invariably slept at right angles to the grass 

 stem or plantain head on which it had anchored 

 itself. 



The blue butterfly sleeps vertically, the heath 

 butterfly, like a man, horizontally. Every small 

 heath butterfly but one which I found was securely 

 anchored on the black or brown head of a plantain. 

 Did they mimic closely in colour or form their 

 environment ? They certainly did not. I was easily 

 able to detect small heaths, after a little practice, at 

 three or four yards' distance, even during the rain- 

 storms. The theory of protective coloration can 

 hardly apply here. 



Why does the small heath always go to bed on 



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