108 N. H. AGE. EXPERIMENT STATION. [Bulletin 171 



have escaped capture were caught by the hens because confined 

 by the screens. Apparently the hens were not disposed to or 

 able to catch flies resting on the inside of the upper part of the 

 screen. 



Later in the summer an additional experiment was carried out 

 with Cages 1, 3 and 4, as follows: 



The same hens remained in each cage. September 12, 100 

 pupae were buried two inches deep in the center of each cage. 



September 15 the surface soil beneath Cage 1 was removed and 

 examined. No pupae were found. 



September 19 the surface soil beneath Cage 3 was removed and 

 examined. Two pupae were found. 



September 22 the soil beneath Cage 4 was similarly examined. 

 Seven pupae were found. 



USE OF CHEMICALS IN THE SOIL. 



Experiments were carried out in 1911 looking toward the possi- 

 ble use of some insecticide in or on the soil beneath infested trees 

 to destroy the vitality of the pupae in the soil or to prevent emerg- 

 ence of the adults. 



In preparation for these experiments various lots of infested 

 apples were placed the prior year both on sod ground and on 

 ground free of sod, and were allowed to decay there. As noted 

 in the table giving results of the experiments, in several cases 

 pupae were buried in the soil before applying the material. 



The area treated in each case was one square j^ard. 



Immediately after making the applications, screen-wire cages 

 were placed over the ground treated, and these were watched 

 daily throughout the rest of the season for adults emerging. 



In estimating results it should be remembered that other ex- 

 periments have since determined that some individuals remain 

 two years in the pupal stage. This does not materially affect 

 matters where ample emergence occurred in spite of the treat- 

 ment given; but in the few cases where emergence was light the 

 cause may have been partly due to this two-year phase. 



As the tabulations indicate, not much of promise was disclosed 

 by the experiments. In two treatments using kerosene emul- 

 sion, and in one of two using Phinotas oil, comparatively few 

 adults emerged. Yet with the emulsion used at the rate of one- 



