356 LÉPIDOPTÉROLOGIE COMPARÉE 



accepted. None of the hybrid larvae vill eat yarrow {Achillea 

 Millefoliuni) or other low plants, so that if the crossings hir- 

 taria cf x zonaria g, povionaria (^ x zonarïa Q, hirtaria cf x 

 grœ caria g occured in Nature, the young larvae would inevitably 

 perish. 



Rearing the larvas. 



I seal the ova, when about to hatch, with a small twig of 

 hawthorn in a glass topped tin box of lo cm. diameter. This 

 sealing is necessary, as the young larvae can get out of any ordi- 

 nary box. When the larvse are in their second instar I sleeve 

 then in a muslin sleeve on a leafy twig of hawthorn. As soon 

 as the larvae are full grown, as can be perceived by feeling them, 

 for when fullfed they are very hard, I transfer them to a large 

 flower pot half filled with tightly pressed, moistened cocoa-nut 

 refuse or leaf mould and cover the mouth of the pot with muslin. 

 When the larvae hâve been buried about six days, I dig them up, 

 and lay them on damp cocoa-nut fibre in tin boxes, such as I feed 

 them in, and put the lid on. I find that then they pupate readily 

 and any tendency to mould is arrested, for dead ones are readily 

 seen and removed. 



Diseases of the larvie. 



The larvae are usually very sturdy and strong until the fourth 

 instar is reached, when a certain percentage nearly always develop 

 a disease, in which the frass is watery and of a bright red colour. 

 When the disease is only slight, it can be cured best by washing 

 them carefully in luke warm water, in which a crystal of potassium 

 permanganate is dissolved, and then isolating the affected indi- 

 viduals, but the best plan is to destroy ail that can be spared 

 as the disease is very infectious. Once the larvae pass the critical 

 stage, they are quite safe. 



