FANCY FLIES. 87 



that is dark claret or tortoise-shell. It is curious 

 to remark that the few flies found on the water 

 in winter are dark. It is a well-ascertained 

 fact, that dark colours attract warmth in a 

 greater de2;ree than lio;ht colours. This is 

 capable of very easy proof by the simple test of 

 placing a piece of dark cloth and another piece 

 of white material on the snow when the sun 

 shines. The snow will be melted to a greater 

 depth under the dark than under the light 

 cloth. Thus can the dark flies live by attract- 

 ing more heat in an atmosphere which would 

 destroy by cold the paler kinds. These winter 

 flies, and many of the spring, summer, and 

 autumn insects, are called black, and so made ; 

 whereas many of them are dark claret colour. 

 No. 11. in Plate Y. would probably be made 

 black by most people. Apply a magnifying 

 glass, or even hold it up between the eye and 

 the light, and you will find it is nothing like 

 black. 



It may sound ludicrous to the uninterested 

 and unobserving when I say that I always 



F 4 



