_**?_ 
Laake et el. ( 165 ) in 1931 reported the results of tests of 
materials as attrectents or repellent?. Beef-liver "bait, 4 ounces, 
t c Hnich 5 gm. of derris p order '-es added,, attracted only 10.8 per- 
cent es many flies as did untreated bait. A mixture of 1 part of 
derris -powder and 9 parts of kaolin attracted 6.3 percent. 
Little ( 182 ) in 1931 corn-pared the insecticidal properties of 
Tenhrosia Virginia na and derris. The pondered root of the devil' s- 
shoestrings suspended in ^-ater at 1:800 and sprayed uoon flies, with 
no spreader, killed from 3.6 to 74.3 oercent (according to the origin 
and treatment of the root). Derris in similar tests at 1:800 killed 
78.2 to 85.3 percent of the flies. 
Campbell (50) in 1932 reviewed unoublished ~ork by Davidson, 
who made 15 tests of rotenone as a stomach poison against flies. 
Sight tests were made in screen cages in a greenhouse and 7 in a 
room of 500 cubic feet. Rotenone was dissolved in acetone and added 
to diluted condensed milk or to a dilute solution of molasses. Cot- 
ton "as soaked in the mixtures and exposed in petri dishes to the 
flies. The food ^es not renewed during a test. Each test was paired 
with a check, in which ^lies were given unpoisoned food. The flies 
used in most of the tests were between 1 day and 2 days old. The 
numbers of flies used per test ranged between 18 and 118. In 5 tests 
all flies were killed in 28 to 72 hours. In 5 other tests more than 
90 percent were killed in 24 to 48 hours. The Quantities of rotenone 
in the cotton ranged from 10 to 100 mg. In one test only 0.8 mg. of 
rotenone was used, but a mortality of 84 -oercent was obtained in 94 
hours. Except in one case, little or no mortality occurred in the 
checks. It was concluded that rotenone will kill flies by way of 
the alimentary tract but that its toxic action is slow. In a few 
additional experiments with rotenone as a stomach poison, David, 
gave the flies a choice of poisoned and unpoisoned milk. As would 
be expected, the mortality was lower than in earlier experiments, when 
the f'.ies had access to noisoned food only. A sa tisfactor;- kill did 
not result after exposure for 2 days. As comparisons were not made 
at the seme time between poisoned foods only and poisoned f'od with 
unpoisoned food, it is not certain that rotenone had a deterrent effect 
on the flies, although such an effect is probable. 
Campbell (50) in 1932 reviewed all ^ork done un to that time '™ith 
rotenone against the housefly. Campbell s ^d Sullivan found that 
this fly was among the species most resistant to aqueous suspensions 
of rotenone. Suspensions of 1:5,000 apparently had no effect on house- 
flies, although "hen the flies were examined under the microscope 
after the treatment, crystals of rotenone could be seen distributed 
over the integument. Against the housefly, rotenone need not be 
lied in suspension in water, but may be applied in solution in an 
•rgenic solvent. Kerosene, so largely used as a solvent end carrier 
for the pyrethrins in household sprays, is not a good solvent for 
rotenone; however, the effectiveness of a saturated solution in kerosene 
Ik s n t yet been determined. It seemed more promisin,: t nix kerosene 
with a solution of rotenone in an organic liquid that is miseible ™ith 
