9 



state, fifteen to twenty days as a chrysalis, and eight to twenty days 

 as a moth or perfect insect. 



The rapid development of the silkworm and its marvelous transfor- 

 mations indicate extraordinary power and very active functions. Its 

 respiration is almost equal to that of the frog and of certain large 

 birds, and it must be always surrounded by plenty of pure air, 



THE FOOD OF THE SILKWORM. 



The leaf of the white mulberry is the natural and the best food for 

 the silkworm. There are many varieties of the white mulberry — some 

 much better adapted than others to commercial silk culture, and some 

 better suited to certain localities. 



CULTURE OF THE MULBERRY. 



As the securing of a food supply is a necessary condition to silk- 

 worm culture, some information on the culture of the mulberry, con- 

 densed from a bulletin of the Bureau of Plant Industry, "■ is inserted; 



Of the mulberry there are many so-called species and a great many varieties, but 

 there are only one or two species and a few varieties which are of importance in 

 silkworm propagation. Chief among these for producing silkworm food is the white 

 mulberry, Morns alba. This is thought by some to be a native of China. It is hardy 

 over a large area of the United States. 



Most of the silkworms reared in China are said to be fed upon Morus multicauMs. 

 This mulberry was largely planted in the United States many years ago. Few, if any, 

 of the original trees remain, but specimens which are thought to be wild seedlings 

 of these are very plentiful in the Southern States. These trees are thoroughly accli- 

 mated and free from disease. It is therefore probable that there is now in the United 

 States an abundant supply of material for propagating purposes, at least. The white 

 mulberry, under good cultivation, is a low-growing tree, seldom attaining a greater 

 height than 2.5 or 30 feet. It will reach this height in a comparatively few years 

 after planting. In the vicinity of Washington the trees flower about the middle of 

 May and ripen their fruit during June. 



The mulberry may be propagated by means of seeds, cuttings, layering, grafting, 

 and budding. Seeds and cuttings are, however, the least expensive and trouble- 

 some, and the most satisfactory means of propagation. 



Propagation by Means of Seeds. — This is the most convenient and rapid method of 

 propagation. To remove the seeds from the berries, place them in a large bucket or 

 a tub and squeeze them with the hands until they form a jelly-like mass. Add 

 water and stir well to allow the seeds to sink to the bottom. The water and pulp 

 can then be poured off, and the seeds can be dried by exposure to the air. 



The seeds may be planted at once, or they may be kept over winter and planted 

 in the spring. Beds about 5 feet wide should be thoroughly prepared. The seed 

 should be sown broadcast, not too thick, as crowding makes weak plants. Press the 

 seeds in with the back of a spade and cover lightly with fine soil. For protection 

 from the heat of the sun, over the beds should be placed lattice-work screens made 

 of lath, and over these canvas should be spread until the plants show above the 

 ground. After that the canvas is unnecessary except in the hottest part of the day. 

 With spring-sown seeds the lath screens without canvas will be suflBcient. 



« Bui. No. 34, Bureau of Plant Industry, U. S. Department of Agriculture. By 

 George W. Oliver. 



4389— No. 165—06 2 



