154 Psyche [October 



Examinations of puparia kept out of doors during the winter 

 of 191*2-13 showed that a few adults emerged during warm weather 

 but the majority of the immature stages appeared to continue 

 developing very slowly and will probably not emerge until the 

 advent of spring. 



Methods of Artificial Propagation of Parasites of the 



Stable Fly. 



As has been shown, the habits of the female parasites enable 

 them to destroy a great number of fly pupa. Many of these pupse 

 are destroyed by the development of the young parasites and others 

 died, apparently from injury caused by the insertion of the ovi- 

 positor. Circumstantial evidence also indicates that many fly 

 pupa? are pierced by the ovipositor to cause juice to exude from the 

 punctures for food for the parasites. This view is strengthened 

 by the finding in nature of numerous Stomoxys puparia, the con- 

 tents of which have completely dried up. 



It would seem that if an adequate number of these parasites are 

 present early in the season they would be quite effective in the con- 

 trol of the stable fly. However, under natural conditions it is 

 reasonable to assume that in general there is seldom a sufficiently 

 great number of parasites present to cope with Stomoxys, despite 

 the fact that the fly generally occurs in small numbers early in the 

 spring. The development of the stable fly is considerably slower 

 than that of the house fly and as a consequence it seldom becomes 

 sufficiently abundant to be very injurious until in the fall. The 

 development of the parasites is slower than that of the stable fly, 

 hence under natural conditions the parasites are unable to control 

 it. However, late in the fall the parasite also becomes very 

 abundant as breeding is facilitated by the great abundance of 

 its hosts and the high temperature which prevails at that season. 

 With the advent of cold weather the breeding of both the parasite 

 and host is checked to a great extent and when fatal temperatures 

 are reached nearly all of the adult parasites are killed without 

 having had an opportunity to deposit in the fly puparia which are 

 still present in rotting straw and other places. This condition 

 allows many stable flies to continue to develop through the winter 

 and appear as adults the following spring. Those which were in 



