■63- 
Insecticide 
Derris-skim milk 
Check 
Lead arsenate- 
flsh oil 
Check 
Lead arsenate-glTie 
bentonite-lime 
Check 
Injured 
: Uninjured 
Larvae per 
Tips in- 
: Control 
tips 
" tips 
injured tip ' 
jured 
Fumber 
Number 
Slumber 
Percent 
Percent 
34 
174 
0.59 
16 
66 
112 
127 
.74 
47 
— 
17 
226 
.53 
• 7 
88 
150 
110 
.64 
58 
~ 
l 
38 
238 
.61 
14 
78 
141 
80 
.74 
64 
The derr is-- skim-milk mixture might have given better results had it 
been properly diluted in the first application. Reference is made to a 
mimeographed circular by C-lasgow, who recommended 1.5 pints of a cube or 
derris extract containing 5 percent of rotenone plus 2 gallons of miscible 
pine oil in 100 gallons of water, the application to be made on June 25 
and July 4 (in New York). Results with derris indicate that the ground 
root is probably better than the extract. 
Potts ( 352 ) in 1936 reported that derris coated with linseed oil (der- 
ris 4 lb. and 8 lb. to 100 gal. with' 1 percent linseed oil) was the most 
effective insecticide, giving approximately 75-percent control. Other in- 
secticides tried were lead arsenate 3:100 and 6:100 with linseed oil; lime- 
sulfur 1:20; bordeaux mixture 4-4-50; nicotine tannate 1:400 with 1 percent 
of linseed oil; and phenothiazine 6:100. In 1937 Potts ( 554 , ' 355 ) reported 
that (a) '1 part of derris resin plus l/2 part of linseod oil plus 8 parts 
of water, .and (b) 1 part of derris resin plus 5 parts of linseed oil plus 
2.5 parts of acetono gave excellent control. Derris and other insecti- 
cides 'were sprayed from an autogiro for the control of this insect. Potts 
( 536 ) in 19 38 reported that the control obtained with derris ranged from 
85 to 99 percent. The mixtures contained' adhesives and spreaders and were 
applied by ground equipment,, Concentrated spray mixtures were much more 
effective than standard spray concentrations and can be applied at a small 
fraction of the cost of mixtures cf ordinary spray concentration. 
The Connecticut Agricultural Experiment Station (78) in 1938 reported 
that two applications of ground derris or cube (4 lbs. per 100 gal,) with 
a suitable spreading and adhesive agent, was much superior to lead arse- 
, with fish oil as an adhesive agent, when the latter was used at the 
rato of 3 pounds per 100 gallons. A modification of the spraying tech- 
nique may make this method of control economically feasible in forest 
plan I I - 
