105 



significantly higher than in the control groups, while dump fly mor- 

 tality remained unaffected. Fifteen 0. aenesoens larvae prevented the 

 development of an equal number of M. domestica larvae, and produced 

 mortality rates of 98.3 and 90.6% when reared with 30 and 45 house fly 

 larvae respectively. House fly larvae that pupated in treatments 3, 4, 

 and 6 reached the adult stage (Table 12). The remaining house fly larvae 

 were prevented from reaching the pupal stage and died as larvae, but no 

 dead larvae could be found in the growth media. This strongly suggested 

 that the larvae of 0. aenescens were preying upon the larvae of M. 

 domestioa. 



Predation study with Ouhyra aenescens. In this experiment, adapted 

 after Peck (1969), the competition studies described above were modified 

 and the availability of the larval medium as a food source was removed. 

 Replications were 180-ml clear plastic cups containing 90 ml of vermicu- 

 lite. Each treatment was replicated four times. Prior to addition of 

 larvae, enough water was added to the vermiculite to make it damp but 

 not soggy. Too much water forced larvae to the surface, not enough 

 water caused them to stick to the sides of the cups. Water was added to 

 all cups daily throughout the experiment to maintain the proper moisture 

 level. The experimental design is shown in Table 13- In treatments i, 

 2, and 3, 10 first- ins tar larvae of 0. aenescens were placed in each 

 cup of vermiculite. Then 25, 100, and 200 first-instar house fly larvae 

 were added daily to each cup in the respective treatment group until 

 pupae were noted in the cups. Treatments 4 through 8 were used as 

 controls. Cups were covered with screen and kept in the growth chamber 

 except when larvae were being added. At the end of the experiment, 

 flies were allowed to eclose and die before they were counted. 



