66 VARIETIES OF DUNS. 



which are seen near the water, is almost black. 

 The early duns are of a very dark olive, whose 

 occasional varieties, as the season advances, assume 

 a lighter brown, while others shine in a heavy 

 blue ; until at length yellow, orange, or cinnamon 

 decks the former, and pale blue the latter, inter- 

 mixed with others apparently compounded be- 

 tween these. With one exception, that of the 

 blue-blow, the ephemera appear invariably to 

 become of a lighter hue as warmth and light in- 

 crease ; and we see the summer duns dressed in 

 bright yellow, orange, red, and cinnamon. From 

 these fresh relays appear, and as the season ad- 

 vances, these again assume the gradatory shades 

 of red, brown, violet, and claret colour. 



" The daily appearance of the ephemera, as 

 well as the colours they shine in, is also under 

 the influence of times and seasons. Excess of 

 cold, as well as of heat, is unfavourable to them : 

 thus in the depths of winter they are not seen at 

 all ; in spring they do not show themselves until 

 towards noon ; while in the meridian splendour 

 / of the summer days, they (to avoid heat) come 

 out in the mornings and evenings principally, 

 and are hardly seen at mid-day. A kind and 

 provident nature so suits the supply of her crea- 

 tures, that her economy may never be disturbed. 

 If these ephemeral flies appeared all of them at 

 one time, the air would be vitiated, and the birds 



