xxii EuRorEAX Butterflies axd Moths. 



The character of the soil also determines that of the Lepidoptcra of a locality as well as 

 that of the plants. Moist and dry districts, and sandy or limestone soils, each have species of 

 Lepidoptcra peculiar to them. Many species are only found inland, while others are peculiar to 

 the sea-coast. But many causes combine to render a species rare or common, apart from out- 

 ward conditions, c\cn where its food-plant is abundant, and the locality apparently favourable. 

 While many species are abundant almost everywhere, others are confined to particular localities, 

 frequently without our being able to discover any reason for this difference. 



The number of individuals of different species is also various. While many species are 

 common in the localities which they frequent, others are scarcer, or are only to be met with 

 more commonly in years which are peculiarly favourable to their development. Many species 

 which are common in the larva state are considered great rarities as perfect insects. A 

 species which has formerly been common often disappears from a locality almost entirely, and 

 re-appears, perhaps, years afterwards, at first singly, and then more abundantly, till it becomes 

 as common as before. This is, no doubt, due to the influence of unusual seasons. The disap- 

 pearance of many of the English fen insects is believed to be due as much to the larvje or 

 pupae having been destroyed by unusually high floods as to the actual drainage of the fens, 

 both causes having combined for their extermination at about the same time. As we 

 advance towards the high north, or to the summits of the highest mountains, we find the 

 number of individuals greatly diminished, as well as that of species. 



The fewest species are to be met with in flat cultivated districts. Many Lepidoptcra are 

 found only in woods, generally in flowery places, or flying round bushes. Others frequent road- 

 sides, others meadows, some prefer barren hill-sides, and often settle on the bare rocks, while 

 others select low flowery places. 



Uses of Lepidoptcra. — The Lepidoptcra which are most directly useful to man are the Silk- 

 worms. These are the larvae of various moths belonging to the families Bombycidce and 

 SatiirnidcF, which spin a thick cocoon, from which we obtain the valuable material called silk. 

 The best known and most useful species is the Mulberry Silkworm {Bonibyx Mori, Linn.), a native 

 of China. Its eggs were brought to Constantinople during the reign of Justinian (a.d. 550) by two 

 missionaries, who concealed them in hollow canes. Since that time the insect has been reared 

 throughout Southern Europe for the sake of its silk, but is only reared as a curiosity in the north. 



Attempts have lately been made to introduce other silkworms into Europe. The best known 

 is the Ailanthus Silkworm {Attaeiis Cynthia, Drury), common throughout the East Indies, which 

 feeds on the Ailanthus Glandnlosa, a tree which is often grown for shade and ornament. It is 

 hardy and easily reared, and has become naturalised in several parts of England and France, as 

 well as in the United States and Australia ; but it yields a small cocoon of doubtful quality, which 

 is veiy difficult to unwind. The Japanese and North Chinese Oak-feeding Silkworms {AntJicrcca 

 Yama-mai and Pernyi, Guer.) yield large cocoons of excellent quality, which are easily unwound ; 

 but they are only reared with great difficulty and uncertainty, and rapidly degenerate in Europe ; 

 so that Bonibyx Mori is still the only silkworm of any economic value which is reared on this 

 Continent. Larvae, pupae, and even moths, form an important article of food among those 

 savages who live partly on insects, especially in Australia. 



Like other insects which frequent flowers, Lepidoptcra probably contribute largely to the 

 fertilisation of the latter by conveying the pollen from one flower to another. 



Injurious Lepidoptcra. — As the larvae of most Lepidoptcra feed on plants, many of them cause 

 great damage to our fields, gardens, and forests. They are generally injurious only when in 

 great numbers, though, in the case of larvae which attack the roots and stems, a very few may 



