32 



The chief cause of the disease is neglecting to change the beds and 

 keeping litter in and around the room. When only one or two worms 

 have died from calcino all the shelves should at once be cleaned and 

 divested of dead worms. The floor should be washed with a solution 

 of sulphate of copper (1 to 200 by weight), and a pound of sulphur 

 should be burned, or a strong wood smoke created in the room, which 

 should then be shut up five or six hours, after which the worms should 

 be fed. Should any worms die the next day the beds should again be 

 changed and an ounce of sulphur burned. The quantity of sulphur 

 fumes that would kill rats, bats, and lizards and even human beings 

 does no harm to silkworms. No hesitation, therefore, need be felt in 

 fumigating the rearing room with sulphur; but eggs and thread nets 

 must not be subjected to sulphur fumes. Silkworms affected with 

 calcino die before the moth stage; therefore, it is impossible for the 

 disease to be hereditary. But loose spores of the mold creating the 

 disease may get on health}^ eggs. These may be washed off by a good 

 bath of fresh water. Some recommend a bath with a solution of sul- 

 phate of copper (one-half per cent of copper). In cases of calcino 

 the room should be disinfected immediate!}^ after the cocoons are 

 gathered and the paper and brush used should be burned. 



As calcino is never due to infected eggs no attention need be paid 

 to the presence of spores of the Botrytis in the microscopic examina- 

 tion to select eggs. 



GKASSEBIE. 



Silkworms having this disease become restless, bloated, and yellow. 

 If punctured they exude a pui*ulent matter full of minute polyhedral, 

 granular crj^stals. 



Grasserie is neither hereditary nor contagious. Unlike pebrine, 

 flacherie, and calcino, it is not caused by microbes capable of multiply- 

 ing and creating plagues. Grasserie does little harm to silkworms in 

 Europe, but in warm countries, as in Bengal, sometimes assumes an 

 epidemic form. 



Worms first fed on mature leaf, and afterward on young leaf, are 

 apt to take grasserie. The propagation of large trees is the best means 

 of checking the disease. The main cause of the sporadic appearance 

 of grasserie is mismanagement of the worms at the molting periods. 

 Feeding should not be stopped before all the worms have begun to 

 molt, and should not be recommenced until all the worms are well out 

 of the molt; otherwise they are likelj^ to have grasserie. This disease 

 often leads to flacherie, and when it occurs in an exaggerated form 

 indicates latent pebrine. 



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