II. DISEASES OF MULBERRY SILKWORMS. 



Introduction. The term " silkworm/' while in reality a vague 

 one, has practically come to mean the mulberry silkworm, the 

 caterpillar of various varieties or species of the genus of moths, 

 Bombyx. There are of course silk-producing caterpillars of other 

 genera, such as the Eri (Attacus ricini), the Muga {Anthercea assa- 

 mensis) and the Tasar {Anthercea mylitta), but the industries 

 associated with these worms in India are so small that they are but 

 little known to the world at large, and even in the silk industry 

 they take a very unimportant place. However, as the subject of 

 our enquiry is " silkworm " diseases, they will have to be considered ; 

 but I propose first to discuss the diseases of mulberry worms, and 

 having investigated these in some detail, it will be found that the- 

 diseases of the less important producers of silk may be disposed of 

 rapidly. 



There are several different species or varieties of mulberry silk- 

 worms, but it would be quite outside the scope of our investigations 

 to enter into an essay on. these and their validity. It will be suffi- 

 cient for our purpose to note that, excepting in Kashmir where a 

 univoltine {i.e., producing only one generation in a year) worm of 

 French or Italian origin is reared, the great majority of the worms 

 reared in India are multivoltine {i.e., producing many generations 

 in a year). There are several different kinds of multivoltine worms 

 reared in different parts of India, such as the Nistari and Chhotapolu 

 of Bengal, yielding a golden yellow cocoon, the Mysore, giving a 

 greenish white cocoon, and the Burmese, spinning a -large loose 

 textured cocoon, but all appear to be on the whole subject in the- 

 same degree to the same diseases, so that it will be unnecessary to 

 treat them separately. 



J The mulberry silkworm is a completely domesticated animal 

 which has been reared by man for at least 4,500 years, and like all 

 domesticated animals — and indeed like wild animals too for that 

 matter though in a much less degree — it is subject to certain 

 diseases and pests. Our knowledge of silkworm diseases is, however, 

 of comparatively recent date. Despite the fact that silk and the 

 rearing of silkworms are referred to in Chinese records said to date 

 back to more than 2,000 years before the Christian era, the earliest 

 definite records of disease are to be found in the first European 

 treatise on sericulture, that by Olivier de Serres published in 1599. 

 Here the susceptibility of worms to disease is clearly recognized and 



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