Clare Island Survey — Lepidoptera. 26 5 



the mainland, to its habitats; and Mr. A. W. Stelfox that of Belmullet, 

 further to the north. This moth has an apterous female of very bulky 

 proportions in comparison with the male ; and besides its inability to fly, it is 

 very sluggish on foot. Hence a colony of these insects is extremely localized, 

 being able to extend its distribution only on foot during the fortnight or three 

 weeks' life of the female, as it wanders in search of its food-plant for the 

 purpose of oviposition. Its looper larvae can similarly progress in search for 

 food ; but the caterpillars of Geometers are usually very sluggish, having 

 protective conformation, and they assume not only the pattern but the 

 attitude of twigs, and their movements are accordingly very deliberate. These 

 peculiarities have resulted in a very isolated and discontinuous distribution for 

 this moth in the British Islands as well as through the European continent. 

 It is, however, numerous where found, and is easily reared. Its European 

 distribution is as follows : — Armenia, Ural Mountains, S. W. Bussia, Hungary, 

 Switzerland, 1ST. Central France, Germany, Sweden. Thus, without being a 

 member of the alpine fauna, it is found on the slopes of mountains, and in 

 Sweden, as well as in the warmer temperate climates of Armenia and S. W. 

 Bussia, in such localities as the banks of the Seine near Baris, and in poor 

 pastures suited for the growth of its low-growing food-plants, such as trefoil, 

 Achillea Millefolium, Centaurea Jacea, Salvia pratensis, &c. Such soils are 

 generally of sandy or stony, and barren nature, and, like sand-hills, are poor 

 in nitrogen and such materials as are required by more luxuriant vegetation. 

 Temperature therefore does not seem an important factor in determining its 

 distribution so much as the requirements of its food-plants. The phenomenon 

 of both alpine and maritime habitats for certain plants as well as insects 

 is thus explicable. Its wide but discontinuous European distribution 

 warrants us in attributing a very great antiquity to an insect with such 

 limited powers of locomotion. A parallel in the vegetable world would be a 

 plant which was devoid of seeds and could only spread by rhizomes. Let us 

 examine its distribution in the British Islands — for though the difficulties 

 appear to be accentuated, the facts when set out before us may narrow the 

 problem to be elucidated. It has not been found in Scotland. In England, 

 which has been well examined by lepidopterologists, only one station is 

 known, namely, sand-hills in Cheshire, not far from Birkenhead. About 

 twenty years ago Mr. D. C. Campbell, of Londonderry, found the larvae at 

 Ballyeastle, Co. Antrim, which I identified ; and the moths were subsequently 

 found in good numbers on the sand-hills there. A few years afterwards 

 Mr. Sheridan, of Dugort, Achill, sent a male specimen which he caught flying 

 on the sand-hills at that place. 



In the year 1896 Mr. Halbert, of the National Museum, Dublin, in 

 company with Mr. Dillon and myself, found a numerous colony at Slyne Head, 



