230 APPENDIX 



peeled, broken up into pieces, covered with water, 

 and slowly brought to nearly the boiling point, or 

 else steamed. The pieces are then put into the old 

 juice. This juice is made in the first instance by 

 adding a little yeast to the water that covers the 

 bananas (after they have cooled). The juice can 

 then be used over and over again if it is occasionally 

 greatly diluted with water to keep it from becoming 

 too acid. The food is at its best from one to two 

 days after being in the juice, although it may be used 

 for a week or more. Keep food in glass-stoppered 

 large-mouthed jars. Scrupulously avoid leaving the 

 margin of the jar wet after removing food. 



Feeding. — When a culture is to be made up the 

 most approved way is to put about a teaspoonful 

 of food on the bottom of the bottle and over it a 

 folded piece of absorbent paper. The flies, while 

 still under ether, may be dropped into a cornucopia 

 of paper which is placed in the bottle. Often, how- 

 ever, the flies are brushed into a dry bottle and the 

 cotton plug put in. An hour or more later, when 

 the flies have recovered, the food, wrapped up in 

 paper, is added. Toweling paper is cheap and serves 

 excellently the purpose of wrapping the food, etc. 



By putting in at first more food than recommended 

 above it is possible to carry a culture to the end with- 

 out further feeding. But more flies and greater 

 accuracy result if a small amount of food is first added, 

 then as much more at the end of six or seven days. 

 When the parent flies are taken out at about the tenth 

 day, food may be added for a third time. New 



