August, ’20] 
STEARNS: LASPEYRESIA CONTROL 
367 
On July 30, after cessation of feeding by third brood larvae, percentages 
of injury were ascertained again by count of infested twigs, the average 
being 13.38. 
The reductions in the amount of injury recorded range from 13.34 
to 44.44 per cent; the average reduction for the entire plot was 14.96 
per cent. The average percentage efficiency for these insecticides may 
be computed as 73.3. Nicotine sulphate (40 per cent) and sea moss, 
arsenate of lime, powder, self-boiled lime sulphur, nicotine sulphate 
(40 per cent) and sea moss, as two individual combinations show each 
an efficiency of 80.0 per cent. 
i 
Table II.—Results with Nicotine and Nicotine Combinations in Field Tests with Single 
Caged Peach Trees Infested by Laspeyresia molesta Busck, Vienna, Virginia, 1919 
Sprays applied July 14 
Per cent 
injury, 
June 23 
Per cent 
injury, 
July 30 
Per cent 
reduction 
in injury 
Per cent 
efficiency 
for spray 
Insecticide 
Formula 
1. Arsenate of lead, paste. 
2-50 
1-800 
4-50 
20.00 
6.66 
13.34 
66.7 
Nicotine sulphate (40%). 
Sea moss. 
2. Arsenate of lead, paste. 
Nicotine sulphate (40%). 
Calcium (3) casein (1). 
2-50 
1-800 
1-50 
40.00 
13.33 
26.67 
66.6 
3. Nicotine sulphate (40%). 
Sea moss. 
1-800 
4-50 
23.80 
4.76 
19.04 
80.0 
4. Arsenate of lime, powder. 
Self-boiled lime sulphur. 
Nicotine sulphate (40%). 
Sea moss. 
i-50 
8-8-50 
1-800 
4-50 
55.55 
11.11 
44.44 
80.0 
Check—no treatment. 
25.00 
25.00 
Unchanged 
Statement of Results 
Nicotine sulphate (40 per cent) diluted 1 part to 800 parts of water 
employed either alone as an ovicide or in combination with an arsenical 
in applications near hatching time has, in detailed laboratory tests and 
in limited field tests with single infested caged peach trees, resulted in a 
more than three-fourths control of Laspeyresia molesta Busck. These 
encouraging results are yet to be confirmed by experiments on an or¬ 
chard scale. 
Life-history studies show that in northern Virginia the heaviest 
deposits of eggs are present on the foliage about May 17, June 21, July 
26 and August 28. Local applications of nicotine sulphate to be most 
effective should be made on or near these dates. 
