LEPIDOPTERA, 233 



of lethargy which resembles death. The dryest and cleanest litters 

 diffuse very soon a sickly smell. This moult lasts from thirty-six to 

 forty-eight hours. During this time the room should be kept to at 

 least 22 Centigrade. 



When they awake out of this last sleep the attendant should con- 

 tinually be on his guard, as it is then that diseases break out. The 

 worms suffering from these different diseases have received different 

 names. There are besides the luisettes the arpians that is to say, 

 worms that have exhausted all their energy in the work of the last 

 moult, and have not even strength to eat the yellow, or fat worms, 

 which are swollen, of a yellowish colour, and which very easily die ; 

 the flats or mous, the soft or indolent ones which, after having eaten 

 a great deal and become very fat, die miserably, and enter into a 

 state of putrefaction. And lastly, it is at this age that the muscardine, 

 which hardly shows itself at any other age of the insect, appears with 

 great intensity. 



The muscardine is a terrible scourge to the rearers of silkworms. 

 The losses which result from this disease in France are estimated at 

 at least one-sixth of the profits. No particular symptom allows of 

 our recognising the existence of this disease in worms which, how- 

 ever, contain its germ ; only, the worm, which has eaten up to that 

 time as usual, appears almost in a moment to change to a duller 

 white ; its movements become slower, it becomes soft, and is not 

 long before it dies. Seven or eight days after its death it becomes 

 reddish and completely rigid. Twenty four hours afterwards a white 

 efflorescence shows itself round the head and rings, and soon after 

 the whole body becomes flour}-. This flour is a fungus called Botrytis 

 bassiana, of which the mycelium develops itself in the fatty tissue of 

 the caterpillar, attacks the intestines, and fructifies on the exterior. 

 This fungus has been considered as the immediate cause of the mus- 

 cardine, and has been also regarded as the last symptom or end of 

 the disease. The communication of the disease by contagion has 

 alternately been admitted and denied. As its true cause, and any 

 efficacious means of opposing it, are still unknown, the breeders of 

 silkworms must be content to apply so as to prevent or struggle 

 against this dreadful scourge the precepts of hygiene : good ventila- 

 tion, excessive cleanliness, frequent dclitements, and good food pro- 

 perly prepared. 



After the muscardine, we must mention another epidemic disease 

 still more terrible, the gattinc. This disease shows itself from the 

 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 



