THE CLOUDED YELLOW BUTTERFLY. 



Not by immigration certainly ; I have given satis- 

 factory proof that the specimens were British born. 

 That they do, like some other butterflies, occasionally 

 come across from France we know full well ; clouds 

 of them have been seen on their way far out at sea. 

 There is no explanation forthcoming yet, we must 

 extend our knowledge of Ediisa as regards its life 

 history both here and on the Continent ; we must 

 accumulate facts and patiently await the answer to 

 our question. There was an old tradition that it 

 occurred in England once every seven years ; this 

 empirical law was founded on scanty observation, and 

 has quite broken down before stubborn facts. We 

 are all looking forward with anxious expectation to 

 the Edusa period of 1878. Will it be one of plenty 

 or scarcity ? If the latter, why ? It is very remark- 

 able that the Pale Clouded Yellow (C. Hyale) was 

 very rare indeed last year, though in 1876 it was 

 tolerably plentiful. Why should it not have occurred 

 as well as Edusa / Closely allied as the two are, 

 both in the same genus, both living on the same or 

 similar food, what are the circumstances in nature 

 that caused one to be abundant, the other absent ? 

 Eggs in abundance must have been left the previous 

 year; we have always supposed the same weather 

 good for both ; where then was Hyale in '77 ? We 

 cannot tell. You see I am asking plenty of questions, 

 and giving no answers to them. My aim is to show 

 what interesting problems there are to be worked out 

 in connexion with these butterflies, and that it is 

 in the power of anyone of us to assist in solving them, 

 by a little patient study of nature. I promised to 

 allude again to the white variety of Edusa known as 



