Van Gundie ( 152 ) in 1936 reported excellent control of the red spider 
with a rotenone' formula that carried approximately 30 percent of sulfur in the 
form of fused bentonite sulfur, which aids as a. sticker for the rotenone and 
also acts as an activator. It should not be applied to conifers until the new 
growth for the season has ceased. If the tips are young, tender, and growing, 
some conifers, particularly hemlock, will be soorched.- 
Consumer' s Research, Inc. (45) , in 1937 recommended rotenone products for 
use against red spiders. . 
Derrisol controls red spiders, according to advertising literature issued 
by the manufacturers, William Cooper and Nephews, and enclosed in a letter dated 
November 16, 1937, to R. C. Roark. ■ ' 
C. L. Smith ( 136 ) in 1937 reported tests of derris sprays against -several 
species of insects. Small-plot tests were made and the derris powder (90 -to 95 
percent passing a 200-mesh sieve; rotenone 4 percent)" plus a "40-T>ercent coconut- 
oil soap was applied with a knapsack sprayer. Against red spiders on 
delphinium plants in the. field, results we're as follows: 
Application "' . Reduction in' 48 hours 
.-.,.' ' Percent 
Derris 3 IK, soap 40 oz. ('anhydrous . - ■ r 
basis) , per 100 gal. ' '..'.. 81 
Derris, 1.5 lb., soap 30 oz. (anhydrous 
basis) , wettable sulfur 1.5 lb. 90, 
Dust, rotenone 0.75 percent 62 
Against red spiders on hydrangea, derris 2 pounds and soap 30 ounces 
(anhydrous basis) per 100 gallons caused 96-percent reduction, as revealed in 
a count made every 24 hours. C. L. Smith's work was reviewed by-Manschke ( 97 ) 
in 1937. 
W e igel and Nelson ( 163 ) 'in 1937 reported that experiments performed against 
the red spider on greenhouse-grown tomato and curumber plants, in which four 
sprays were applied at 4-day intervals, §:eve the following results: A derris 
spray having a rotenone content -of 0.Q056 percent was -as effective as one with 
0.0112-percent-rotenone content; the derris 'sprays used were superior to cube 
sprays of the same rotenone content, the differenee being -explainable on the 
basis of the total-extractives content, ^hich was 18.6 percent for the derris 
and .12.3 percent for the cube; the addition of -oyrpthrum extract did not 
improve. the effectiveness of the sprays against the red spider'; with sprays of 
the same rotenone content, containing sulfonated castor oil 'as a spreader, the 
result was a better kill than when either alkylphenylberazenesulfonic acid or 
rosin residue was used. In a second series of experiments the same insecticides 
that were used in the first series, but applied four times at weekly intervals, 
gave approximately the. same results, except' that on tomatoes the spray contain- 
ing derris, pyrethrum, and alkylphenylbenzenesulfonie acid appeared to be as 
