CHAPTER V. 
ENEMIES AND DISEASES OF THE SILK-WORM. 
As regards the enemies of the Silk-worm but little need be said. It 
has been generally supposed that no true parasite will attack it, but in 
China and Japan great numbers of the worms are killed by a disease 
known as “uji.” This is produced by a Tachinid called by Rondani 
Ujimyia sericaria, and the life history of which has been carefully worked 
up by Prof. C. Sasaki of Japan (Journal Science College, Imp. Un., 
Tokio, Japan, 1886, Vol. I, part I). 
There are, however, several forms of disease against which it is nee- 
essary to guard and of which it is therefore necessary that silk-raisers 
should have an intimate knowledge. Through the multitude of local 
names given to these diseases abroad, one would suppose that there 
were as many diseases.to which the Silk-worm is subject. But Pastenr, 
after studying the subject very carefully, concluded that all may be con- 
sidered as varieties of four principal diseases, viz: the muscardine, péb- 
rine, flacherie, and grasserie.* 
The gattine, one of these varieties, is considered by Pasteur as a mild 
form of the pébrine,t but Maillot, in a later work,t considers it as a 
species of the flacherie. 
These diseases are found to some extent intercurrent, though at all 
times one (at least one of the first three) has been more prevalent than 
the others, generally amounting to a plague. So in 1849 we find M. 
Guérin-Méneville studying, on the part of the French Academy, the 
then prevalent disease, the muscardine. This was soon followed, in the 
fifties, by a veritable scourge in which the pébrine was the leading feat- 
ure, with flaccidity (flacherie) quite frequently found. The same learned 
body appointed Pasteur to study the causes of these diseases, and after 
two years of patient research he devised a means, which will hereafter 
be described, of successfully preventing the return of the pébrine. This 
made way for flaccidity, which is to-day the dread of silk-raisers, for 
although it does not reach the importance of a plague, its effects are | 
distinctly visible upon the national crops of cocoons in France and Italy, 
and I have never known it to be absent from worms reared by me al- 
most every year for nearly two decades in this country. The grasserie 
has never attained any such importance. but occurs in rare instances 
only. 
* Pasteur, ‘ Htudes sur la maladie des vers & soie,” Vol. 1, p. 225. 
t Pasteur, ‘‘ Htudes,” etc., Vol. I, p. 12. | 
t Maillot, ‘‘ Legons sur le vers a soie du murier,” p. 109, 
