Muscidae 433 



ment for providing it is a wide-mouthed bottle filled and inverted over a 

 petri dish lined with filter paper. The only food which is essential is 

 sugar. But if oviposition is desired some protein should be fed. A 

 cake of Fleischmann's yeast, moistened occasionally, will last for several 

 weeks. Boiled egg, chopped fine, is also recommended twice a week. 

 In order to secure Muscina eggs, place a pan containing a suitable 

 larval food in the fly cage after the flies are 12 days old. A satisfactory 

 larval diet may be prepared as follows: 



Alfalfa leaf meal 6 parts 



Soybean meal i part 



Water 1 1 parts 



Boil all together 10 minutes. Add dried skim milk. . i part 



(All of these materials may be purchased at a feed store; cost for large scale 

 production, about 5 cents for 4000 maggots.) 



A pan containing 3 to 4 cups of this ration, placed in a fly cage for 

 2 days, should secure enough oviposition to produce several hundred 

 full grown larvae in 8 to 10 days under summer conditions. (If the 

 larvae are too abundant for the quantity of food they will not develop 

 to maturity, and more food should be added.) The larval medium 

 should be kept moist while the larvae are growing, but when ready to 

 pupate they require a semi-dry medium, and sometimes additional 

 space — not more than 300 in a pan 6 inches in diameter, so that all 

 pupation chambers may be in one layer at the surface. 



The temperature recommended for larval development is 72 ° to 

 76 F. 



If it is desired to remove full grown larvae from the food substance, 

 for laboratory purposes, place the culture in a basket made from screen- 

 ing, 8 meshes to the inch, and wash in running water or in a basin of 

 water. 



There are many other combinations of meals and vegetable products 

 that are satisfactory for larval diets, but the following requirements 

 should be considered: The mixture should be sufficiently porous to 

 allow escape of noxious gases, and to provide air for respiration. The 

 protein concentration should be relatively low, to minimize disagreeable 

 odor. The ration should be sufficiently nutritive to promote rapid 

 growth, in order that the flies may escape infestation by mites. The 

 consistency should not be glutinous, so that the particles will separate 

 readily in water, if the maggots are to be removed from the media by 

 washing. 



Very frequently a thick growth of mold appears on the surface of the 

 larval medium after 3 or 4 days; but a healthy crop of maggots will 

 soon demolish it, and no harm seems to be done. 



