[ 175 3 134 



times spontaneously from over distension. Their bodies are als« 

 covered with a viscous oily humor, which transudes the skin. Mr. 

 "Nysten says, that it is owing to the too glutinous nature of the food 

 a;iven to the worm in the second and third ages; because he has seen 

 the disease attack worms when thus fed, which those that had eaten 

 tender leaves escaped; and from the prevalence of the disease in Pied- 

 mont, and in the Department of the Mouths of the Rhone, where the 

 SpaP-ish mulberry, which has hard and large leaves, is cultivated, 

 whilst it is seldom seen in the Department of the Drome and Isere, 

 where that variety of the mulberry is rare. If this theory be correct, 

 (and it certainly is very rational,) the remedy is obvious: to feed the 

 worms in their three first ages with tender leaves, and to avoid the 

 variety of mulberry mentioned: this, by the way, it is thought, has 

 not been introduced into the United States. 



The Lusette. — About the fifth age, silkworms are sometimes attack- 

 ed with a disease called lusette, or claireite, from the shining appear- 

 ance of their bodies. Their heads also increase in size; they cease 

 growing, and die without forming cocoons. On opening them, their 

 stomachs are found full of a glairy transparent fluid, without any re- 

 mains of food; and hence it has been justly ascribed to a neglect of 

 the supply of mulberry leaves. This theory was proved by Mr. 

 Nysten, who produced the disease by starving some worms for twenty- 

 four hours. The means of prevention and of cure are therefore ob- 

 vious. Care should, however, betaken to separate the affected worms 

 from the healthy ones, and to supply them with food in a gradual man- 

 ner, to prevent an opposite disease arising from too sudden repletion.* 



The Yellows. — This disease appears toward the end of the fifth age, 

 when the worms are filled with the silky fluid, and are about to spin. 

 The Abbe Sauvage ascribes it to exposure of the worms to sudden and 

 ercat heat. It consists in a yellowness and swelling of the body, an 

 enlarn^cment of the rings, an appearance of the feet being drawn up 

 from the puffiness of the surrounding parts. The worms also cease to 

 eat, and run about, leaving stains of a yellow fluid, which exudes from 

 their bodies. The yellowness first appears round the spiracles, or 

 breathing holes, and gradually difiuses. It is a kind of anasarca or 

 dropsy of the skin, arising from the infiltration of the nutritive fluid 

 through every part of their bodies. The insects soon become soft, 

 and burst. The acrid humor issuing from them, will kill any worms 

 that touch it. Sauvage also ascribes it to a defect of transpiration, to 

 indi«^cstible food, and to exposure to cold during rainy weather; and 

 directs to dry the air of the apartment, by lighting fires in the chim- 

 ney of the apartment during rainy weather. The yellows or jaunesse, 

 ond the grnsseric, are deemed the same disease by Sauvage and Nys- 

 ten: but the grasseric is more serious when it occurs during the moult- 

 ingjjj^an when it takes place towards the last age. In the former, it 

 is ^fgenefial d i seasc ; in the latter, it is merely accidental. Whenever 



f 



•■('Recher'-.lu's siir \x Maladies des Vers a Soie, par P, II. Nysten, p. 116. "Pes Vers 

 a ^o''-.', piii M. Reynuud, p. Ill, Pi-ri-s, 1834. 



