142 The Irish Naturalist* April, 



Among insects we see the same tendency illustrated in 

 several ways. There is the undoubted fact that a considerable 

 number of butterflies which are double-brooded in the conti- 

 nental parts of their range become single-brooded in parts — 

 especially in the outlying parts — of their Britannic range- 

 The Small Heath butterflj T (C&nonympha pamphilus) was 

 alluded to in the Irish Naturalist 1 some years ago as a common 

 insect which is regularly double-brooded in England, but 

 single-brooded in at least the northern half of Ireland. In 

 more southerly Irish counties it certainly produces two broods ; 

 but I think the autumnal brood (at any rate in Co. Wexford) 

 is generally a poor one. The Dingy Skipper (Thanaos tages), 

 a ver} 7 local Irish insect which I find fairly common in Kil- 

 loughrim Forest, Co. Wexford, in May and early June, does 

 not seem to me to produce any second brood during August 

 in its Irish haunts, as it does in England; and I notice that 

 the Rev. W. W. Flemyng has recorded 2 a precisely similar ob- 

 servation regarding the Holly Blue (Polyommatus argiolus) in 

 Co. Waterford. Whether this form of decreased fertility would 

 make extinction more easy I do not say ; but it is not the only 

 form which the tendency takes even among the Eepidoptera. 

 The Clouded Yellow butterfly (G? //as edtisa), though generally 

 rare in Ireland, sometimes occurs in our fields in swarms, and 

 under rather peculiar, and, I think, interesting circumstances. 

 I remember it in Co. Wexford in 1876. I had never seen it 

 before. The first arrivals that yearw r ere in earl} 7 June : I shall 

 never forget the tantalising sight of a bright golden insect 

 rushing madly by as if speeding for its life, and in a very few 

 seconds lost again to view. Just one at a time to-day, another 

 a few days later, not one that would linger or give me a chance 

 to take it — not one that would even swerve from its direct line 

 of flight. Now obviously these were immigrants from across 

 sea, and they seemed not to have yet exhausted their migratory 

 impetus when I saw them. Then a lull : I had thought I 

 should see no more of the winged gems, when August came. 

 In every clover-field, in every stubble-field, quantities of 

 Clouded Yellow butterflies, so easily netted that on cloudy 



1 vol. iii., pp. 44 and 223. 



2 Irish Naturalist, vol. xi., p. 172, 1902. 



