-82- 
German (95) in 1939 reported that in field experiments in Con- 
necticut, dusts containing 0.5 percent of rotenone, although successful 
in 1937, failed to eaua.l that performcnce in- 1938,' partly "because of the 
heavy July rainfall. High tempers tures and humidities destroyed the 
rotcnone rapidly, and flies ^ere able to ley large numbers of eggs des- 
pite the 10-day interval of application, <-y.ich theoretically should "be 
ample considering the material and the nature of . the insect. The 
addition of sulfur to the dust did not improve it. In 1939 German (96) 
reported that in the hottest part of July 1938, ap-les ^ere dusted with 
rotenone dust and exposed to sunlight 1/2 day. By the end of that pericd, 
the killing po^er of the dust had disappeared, indicating a very rapid 
dissipation of its toxicity. About the only place for dusts of the kind 
mentioned (0.5 percent rotenone) is in late e-oplicp tions after the first 
of August, i_T hen flies need to be destroyed on early ripening varieties 
such ^s Gravcnstein or Wealthy, and excessive residues should be avoided. 
Lathrop ( 169 ) in 1939 reviewed the 10 years of warfare against the 
.blueberry maggot. Under the heading "Farther Investigation Needed", he 
states that studies of rotenone insecticides arc of interest to the. "blueberr; 
producers. 
The United States Department of Agriculture, Bureau of Entomology and 
Plant Quarantine ( 295 ) , in 1939 reported ~ork done in 1938 by ?. J. Chap- 
man on the control of the apple maggot in the vicinity of pou-hkeepsie, 
N. Y. Cube povrder (4.4 -nercent rotenone and 22.9 -orrcent total extractives) 
at the rate of 3 pounds per 100 gallons plus 1 pound o^ ; soybean flour r?s 
applied five times, but permitted an infestation ranging from 34.3 to 93. -i 
percent* Lead arsenate followed by zinc arsenate and t'-o applications of 
■ohenothiazine s,svq the best control. 
Gsrmen and Tcmsend (98) in 1940 reported on the control of the apple 
•maggot in Connecticut. A derris-pyrophyllite dust (0.5 percent rotenone) 
plus 4 percent of vrhite lubricating oil applied as a dust '-.-as effective. 
Although it appears too early to make specific recommends tions con- 
cerning the use of rotenone insecticide? far control of the arvple maggot, 
it seems th'-t such materials may have a. place late in the season r 'r en it 
is desirable to avoid poisonous residues. They "ill doubtless be more 
successful in dry than in --et season, and it should be ke^t in mind that 
combinations so far pre-nered lose their potency, even in dry -eather. 
They are not kno^n to last more than 4 or 5 days on the trees. The extreme 
repiditv of killing action is in favor of rotenone dusts, as sho^m by 
cage tests, ^hich freauently gave 100-pcrcent knock-doms in 24 hours. 
Field observations indicate the same rapid destruction of flies in the 
orchard. Flies coming from unsnre.yed trees outside the orchard still 
remain a problem, but there is reason to believe that the chance of 
elimin- tin.T late comers ^ith rotenone dusts is very Tood. 
