1913] Pinkus — History aril Habits of Spalangia Musdlarum 155 



the larval stage at the time the adult parasites were destroyed 

 would be entirely exempt from attack as well as some of the 

 pupse which had not been reached up to that time. Of course 

 the parasites which are in the immature stages would be protected 

 by the same conditions which protect the host and they would pass 

 the winter successfully and emerge along with the flies in the 

 spring. However, their numbers would be much smaller than the 

 stable fly at that time. 



By artificial means it is possible to propagate these parasites 

 in large numbers throughout the winter and liberate them early 

 in the spring. By this procedure it might be possible to cut down 

 to a great extent the first generation of flies and the continued 

 development of the parasites during the spring and summer would 

 tend to control the flies throughout the year. In addition to the 

 destruction of the stable fly, house flies and other injurious species 

 would also be attacked whenever the parasites are able to reach 

 them. 



Since Spalangia does not discriminate between various species 

 of fly puparia the work of artificial propagation is greatly facili- 

 tated. The writer has found it best to collect the larvse together 

 with the manure or other substances in which they are breeding 

 and after pupation has taken place to separate the pupae and supply 

 the parasites with them. 



The writer has modeled a parasite breeding cage (Fig. 1) 

 which he finds quite practical for the breeding of these parasites. 

 In the construction of this cage an empty honey box (the con- 

 tainer of comb honey) size 8 x 14 x 9| inches in height is used. 

 Glass is closely fitted in the front and top and a hole four inches 

 in diameter is cut in either end. Around the inside edge of each of 

 these holes is tacked one end of a cuff of soft muslin cloth. These 

 cuffs should be about nine inches in length, the outer end being 

 gathered with an elastic so as to closely fit around the wrist of the 

 operator when the hands are inserted into the box. When not in 

 use the cuffs are closely tied with a string to prevent the escape of 

 parasites. At the center of the bottom of the cage a hole one inch 

 in diameter should be cut. The entire bottom of the cage, with 

 the exception of the circular hole, is then covered with oil cloth 

 to protect the wood from the moisture. On top of the oil cloth a 



