-33- 
kerosene, the^- mixed solvents carrying a higher percentage of rotenone 
in solution then would kerosene alone. Dfvidson tested a 1:2,000 
solution of r-otenone in kerosene-ethylene dichloride in a standard 
fly chamber f(6 ft. by 6 ft. by 6 ft..) at temperatures ranging from 
69° to 88° F. Five tests "-ere run and each test m as paired with 
a check of the mixed solvent without rotenone, From 11 to 33 cc. 
of the liquid was sprayed into the chamber, half of it through a 
hole in one side and half through a hole in the opposite side. The 
mixed solvents alone had little or no effect on the flies, but the 
rotenone solutions paralyzed from 29 to 84 percent of them in 10 
minutes, depending on the volume of the solution sprayed into the 
chamber. Commercial pyrethrum fly sprays, rhen tested in the same way, 
paralyzed a larger percentage, but rotenone sprays may kill a greater 
percentage of those effected. In Davidson's test with 33 cc. of the 
rotenone solution, 43 out of 51 flies were brought down and 42 of these 
died. 
Campbell and Sullivan compared the effects on houseflies of 
1:10,000 solutions of the pyrethrins and of rotenone in absolute 
alcohol. A very marked difference in the initial and final effects 
of the sprays was observed. At first all the flies were paralyzed 
by the pyrethrins, whereas none were visibly affected by rotenone. 
Then, as the flies treated with thepyrethrins began to recover, those 
treated '"ith rotenone began to be affected. After 24 hours practi- 
cally all the flies treated -'ith thepyrethrins had recovered, whereas 
a considerable number were dead or dying from the effects of rotenone. 
The final 48-hour count' showed 2-percent mortality for the pyrethrins 
and 22-percent mortality for rotenone. It might be advantageous to 
e -Pply the pyrethrins and rotenone together in order to utilize 
simultaneously the rapid paralyzing action of the one and the slow 
killing po--er of the other. From a toxicological point of view it 
would be desirable to test the pyrethrins and rotenone together and 
separately in order to determine to what extent their combined effect 
is additive. 
Houseflies were being used by Canrobell and Sullivan as test 
insects for the determination of the relative toxicity of rotenone 
and related compounds. The sioreying chamber consisted of a glass 
cylinder 8-1/2 inches in diameter and 17 inches high, and a bell 
jar of the same diameter and 1.7 inches high, w^ich rested on top 
of the cylinder. The cylinder stood, on a shallow copper tray in 
which the flies were confined. The top of the tray could be opened 
or closed at -'ill by a sliding co-per plate. A spray gun was mounted 
in the hole at the top of the bell jar and connected with a com- 
pressed-air line. . The flies in the tray at the bottom of the cylinder 
could be sprayed directly, or by manroula tion of the copper olate 
could be exposed for any de?ired period to a settlinc fog of the 
spray. Treatments could be made in tie cold or at room temperature. 
When the treatments were made in s cold room zt 32° F. , 50 immobile 
flies were placed on their backs on a circle of filter naucr on the 
bottom of the tray. After the. tre; trnent the flier, were transferred 
to cages placed immediately in a high- temperature room at 83° to 
