AGRICULTURAL INDUSTRIES, 



199 



ture/ a very few observations in connection with the foregoing will 

 suffice. We learn from the well-known and already quoted work 

 of Richthofen, that in China in olden times it was strictly forbidden 

 to gather two silk-harvests in one year, or as we should say, rather, 

 to cultivate Bivoltini. In other silk-raising countries this species 

 was held in those days in the same small esteem. It would 

 seem that their cocoons are light and the thread weak. According 

 to Haberland, the Japanese Bivoltini (white and green-spinner) 

 contain only 9*18 grammes, or 1 1 per cent, of the weight of silk 

 of the cocoon. The worms form their cocoons thirty days after 

 hatching ; fifteen days later the butterfly appears. Their eggs are 

 smaller than those of other species, are red in colour and oblang 

 in shape. Ten days after they are laid, the worm is hatched, and 

 begins a second breeding on the same plan as the first. The 

 cocoons are usually of a long ^gg shape, pointed at one end. 



Besides the various diseases common to silkworms, Japanese silk- 

 culture suffers most from a parasitical insect, the larva of the 

 Udschi fly {Udschiuiya sericariciy Rond). According to C. Sasaki,- 

 this fly lays its small oval eggs about the beginning of May 

 along the ribs of the under-side of the young mulberry leaves. The 

 silkworm feeding on these leaves, many of the eggs are conveyed 

 to the alimentary canal, where a thin white worm is hatched,, which 

 • by means of its sharp mandibles, furnished with small bristles, 

 bores through the walls of the canal and reaches the ganglia, where 

 it feeds upon nerve cells. Later it enters the trachea and fleshy 

 substance, and here it attains its maturity, coming finally forth 

 upon the outside surface a full-grown insect. Very often it begins 

 its course later on in the life of the worm, and continues its develop- 

 ment in the chrysalis. The light-weight cocoon which results from 

 its depredation is at last made quite useless by the piercing through 

 of the full-grown fly. Killing the cocoon as soon as quite formed 

 hinders the complete destruction of such as still conceal the living 

 parasite within. 



Greeven,^ some ten ye'ars since, called attention to these insects 

 and their great depredations. He states that sometimes 80 per cent, 

 of the cocoons reserved for breeding have been found to be infested 

 by them, Bavier also, in his book upon the silk industry of Japan, 

 devotes some space to the subject, and notes that an average of 

 forty per cent, of the worms in Sinshiu (Shinano), and in Musashi 

 and Joshiu (Kotsuke) 50 per cent, are injured by these parasites. 



In view of this pest, the various diseases which have up to 

 this time interfered with the silk culture in Japan have seemed 



^ Until now the white Bivoltini have been cultivated only in the neighbour- 

 hood of Miharu, Province Iwaki. 



2 Udschimya sericaria, Rond. "A Fly Parasite on the Silkworm." Nature, 

 Sept. 4, 1884. 



^ " Mittheilungen der Deutschen Gesellschaft Ostasiens." Heft. 7, pp. 20 and 



