In the 1966 test, the vapor generator was operated under actual working 

 conditions in the larger cellar. Trapping records had indicated that this cellar had a 

 more severe infestation problem than did the smaller one. During operation, the 

 generator was 6 feet above the floor at one end of the cellar. The test covered a 

 period of 14 weeks, but no treatments were made during the 1st, 6th, and 11th weeks 

 for the purpose of comparing trap catches. The total number of hours the generator 

 was operated per week was gradually increased from 2 1/2 to 20 1/2 (table 3). 

 Treatments were made twice a week for the first 5 weeks of operation, three times a 

 week for the next 4 weeks, and daily for the last 2 weeks. 



Three methods were used to evaluate the results of the vapor generator tests. 

 The first method was by using drosophila traps &/ made of pint or quart jars baited 

 with dried figs, yeast, and water. A cheesecloth and paper basket fitted into the neck 

 of the jar prevented the flies from reaching the bait. A few drops of dichlorvos, 

 placed in the basket to kill the insects, made counting easier. Traps were examined 

 three times weekly in 1964, and daily except weekends in 1965 and 1966. Dead flies 

 from the traps were taken to the laboratory and counted. Fresh traps were put out 

 at weekly intervals. In the larger cellar, a trap was placed at each end. Controls 

 were single traps in two other cellars that were not treated. In the smaller cellar 

 only one trap was used, and another trap in a small room used as a cellar was the 

 control. 



Trap counts were used in various ways to evaluate the tests. Counts made 

 before treatments and during weeks that treatments were not made served for com- 

 parison. Ratios between numbers of trapped flies in treated and untreated areas were 

 also used. Another use of the trap counts was to determine when treatments were 

 needed and if they had been effective. A trap count of more than 25 drosophila per 

 day per trap was taken to indicate that an area should be treated. Also, after a 

 treatment, the day a single trap count exceeded 25 flies, the treatment was deemed 

 ineffective at that time . 



The second method of evaluation was by the mortality of caged insects placed in 

 the cellar during treatments. Cages were made of 40-mesh stainless steel wire 

 screen molded into a 3/4-by 3- inch tube with a cork stopper at both ends. Cages wer( 

 exposed only when the vapor generator was operating. One cage was placed in an 

 untreated cellar as a control. 



6/ Yerington, A. P., and R. M. Warner. Flight Distances of Drosophila 

 Determined with Radioactive Phosphorus. Jour. Econ. Entomol. 54(3): 425-428. 

 1961. 



