XXXIII 



or white butterflies feed on the Cruciferae, those of Colias in the her- 

 bacesus Leguminosae, of Argynnis on Violets, of Thecla on trees and 

 shrubs, of Melitaea on plantain and allied plants, of Satyrus and Hes- 

 peria on various species of grass. Two allied species of Vanessa, uv- 

 ticcz and polychlows, feed respectively on the nettle and the elm, 

 belonging two allied genera of plants. 



The number of butterflies which have been described from various 

 parts of the earth is very great, equalling that of the birds, both being 

 over 7,700, but by far the greater number of butterflies come from the 

 East Indies, and tropical America. A single genus, Papilio, contains 

 over 500 species, but only 4 of these occur in Europe. 



Some of these insects have afforded materials to several entomolo- 

 gists for the production of elaborate memoirs upon their anatomy. 

 Swammerdam especially, (in his History of Insects), investigates that 

 of the Large Cabbage-white and the Small Tortoise-shell. Herrald 

 has also studied the former species, tracing the variations which its 

 internal organs undergo during the process of transformation. 



That weather has an immense influence upon insect life cannot be 

 denied, especially with regard to butterflies. Thus we find plenty of 

 them sporting about in all directions in fine hot weather, and enjoy- 

 ing the beneficial warmth of the genial sunshine. On the other hand 

 in. cold wet summers we come across very few. There are of course 

 notable exceptions, for instance the remarkable swarms of Vanessa 

 cardui during the wet, sunless, and ungenial season of 1879. Another 

 species which was also abundant that year was Hipparchia cegeria 

 This insect is remarkably fond of shade and moisture, the wet climate 

 of Dunegan in the Isle of Skye seeming to be well adapted to its re- 

 quirements. On the other hand a wet year is not necessary for an 

 abundance of Cardui, as it was excessively common in 1826 and 1884; 

 years which had very fine summers and autumns. 



The wettest years of the present century are: — 1815, 1836, 1848, 

 1852, i860, 1872, 1879, and 1888. The wettest seven consecutive 

 years are those from 1879 to 1881, years bad alike to the farmer and 

 to the entomologist. No others are known. There are however two 

 instances of five consecutive wet years— 1772 to 1776 and 1827 to 1831. 

 1772 to 1776 had a mean excess of 17 per cent, 1827 to 1831 of 9 per 

 cent, 1875 to 1881 of 13^-per cent. The dryest years of the present 

 century are : — 1800, 1808, 1826, 1834, l8 44> l8 54> l8 55> l8 5 8 > 1864, 

 1868, 1870, 1874, 1884, and 1887. 



