236 THE INSECT WOULD. 



very beginning of the rearing, and increases in intensity at each 

 age, so that the number of worms able to enter regularly into the 

 moult becomes smaller and smaller. We are still in a state of 

 utter ignorance as to the cause of this last affection, which has 

 occasioned, for the last ten years, incalculable losses in the rear- 

 ing houses, which threatens the silkworm with complete destruc- 

 tion, and which in the meanwhile has ruined the unfortunate 

 countries of the Cevennes, the principal seat of sericiculture in 

 Prance. 



During the fifth age, the worms become large so quickly that 

 on the fifth or sixth day they are obliged to be moved away from 

 each other on the litter. The delitement must be made every two 

 days, or, indeed, every day now, on account of the enormous 

 amount of the excrement ; and, at the same time, a good venti- 

 lation must be constantly maintained. The temperature of the 

 room should now be kept to 24, without ever exceeding this 

 degree of heat. When it is perceived that the worms wish to 

 ascend or mount, there are placed on the tables, at certain distances 

 from each other, little sprigs of heather, or very dry branches 

 of light wood. 



When the worms begin to mount into the heather, one must 

 encabaner, that is to say, form with these branches little hedges, 



Fig. 213. Sprigs of heather arranged so that the silkworms may mount into them. 



curved back like a hut or cradle, the openings of which are, 

 on an average, seventeen inches or so (Fig. 213). At the 

 expiration of twenty-four hours, all the good worms have 

 mounted. The laggards who remain under the cabanes are 

 taken off by hand, and placed on a table, which is immediately 

 encabaned. 



