HINTS ON SILKWORM-BEARING IN THE PUNJAB. 19 



27. Silkworms are liable to certain infectious diseases, Disea*of 

 of which four are important. Every rearer ought to be 8ilkwopms ' 

 able to recognise these diseases, to know the causes which 

 produce them, and also the simple measures, the adoption 

 of which in time will prevent the spreading of the infec- 

 tion from unhealthy to healthy worms. There is no known 

 cure for any of these diseases, and affected worms can not 

 be saved. Below are given these four important diseases : 



(1) PEBRINE. 



This disease is the most serious of all. It is hereditary. The 

 eggs laid by pebiinized moths are infected ; and the worms which hatch 

 out from them all perish towards maturity. 



The only preventive measure is to rear healthy seed, which has 

 been laid by untainted moths. There is no fear of this disease, when 

 healthy eggs laid by microscopically examined disease-free moths are 

 used, 



Worm born from healthy seed may also contract this disease during 

 life, but this does not always prevent their spinning^ as the disease 

 reaches its climax and kills the worms 30 days after infection. 



Black spots on the body are the outward characteristics of the 

 disease ; internal signs are oval corpuscles, only visible through the 

 microscope. 



(2) FLACHERIE. 



This fatal disease manifests itself after the worms have passed 

 their fourth moult when they are mature and even while spinning. All 

 of a sudden without any apparent cause the victims begin to languish : 

 then become completely still and soon die. They turn black after 

 death and become putrid. The principal causes of the disease are (t) 

 eggs becoming spoiled through careless preservation ; () hereditary 

 tendencies ; (fit) feeding 1 on wet, dewy, dusty or fermented leaves ; 

 (iv) sudden change of diet from tender leaf to tough leaf ; () lack of 

 ventilation ; (vi) excessive heat, i.e., above 80 F. ; (vii) worms having 

 been kept too thick ; (viii) putrifying worms forming a medium for 

 micro-organisms and infesting the others. If these causes are avoided 

 flacherie is not likely to invade a rearing. 



To prevent contagion (i) silk worm eggs should be dipped in a 

 solution of copper sulphate before being incubated ; (tt) sick and dead 

 worms should be regularly picked out and buried deep in the ground 

 at a distance from the rearing house ; (tit) in cleaning the matting 

 powdered lime or copper sulphate should be applied where a dead worm 

 is seen 



(3) MUSCAEDINE. 



This is the most contagious of all silk worm diseases and is 

 caused by the growth of a mould fungus in the Hody of the insect. The 

 chief cause of the disease is neglect to change the beds and the keeping 

 of litter in and around the room. 



