6 4 



SILKWORMS. 



cocoon, and then considering as females those above the average, 

 and as males those that fall below it. 



These arrangements having been completed, the rest of the 

 pupas, which will form by far the larger proportion of the whole 

 stock, must be killed. This is done by placing the cocoons in 

 wicker baskets in an apparatus where they are exposed for about 

 twenty minutes to the steam of boiling water. Fig. 20 shows a 



section of such an apparatus. 

 Below is seen a small furnace 

 which heats the water in the 

 vessel just above it, the steam 

 from which passes through the 

 trays containing the cocoons, 

 and issues at jets at the top. 

 When thus killed they must be 

 thoroughly dried first by expo- 

 sure to the sun and then by 

 being strewn on wooden shelves 

 in the shade, where they can 

 have plenty of air. They are 

 occasionally stirred to give all 

 an equal chance, and then after 

 a couple of months they will 

 be quite dry and may be kept 

 any length of time, provided 

 they are preserved from the 

 attacks of rats, mice, and 

 beetles. Cocoons in which the 

 pupa has been killed are said 



to be "choked," while those 

 in which it is still alive are 

 called " green." This, of course, has nothing to do with the 

 colour of the cocoon. 



Amateurs usually do not take the trouble to separate breeding 

 cocoons, but reel all they have, until only a thin shell of the 

 cocoon is left covering the pupa; they are then placed, with or 

 without the remains of the cocoon, on a bed of bran in a box, 

 where they are kept till the moths issue. 



In about a fortnight or three weeks from the time of com- 

 mencing the cocoon, the moths will begin to appear. Like the 

 caterpillars, they make their entry into the world in the early morn- 

 ing, from four to eight o'clock. As they appear, they should be 

 seized by the wings and placed in boxes, so as to keep the sexes 

 apart for a time. The males may be known by the incessant 



Fig. 20. Section of stifling apparatus. 



