378 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



March 21. Other applications at the same strength appHed earlier 

 in March and throughout the season show a much lower percentage of 

 kill, some as low as 48 per cent (Expts. 38, 39 and 40, Table I, Expt. 

 21-p, 22-p and 23-p, Table II). Three years of careful study at the 

 laboratory and in the orchard convinces us that this miscible oil is 

 not an efficient agent for killing eggs of plant lice occurring on apple 

 trees. 



Crude carbolic acid and various cresols used in different experiments 

 in 1917-1918 were again used during the past season on the eggs of 

 A. avence and some on the eggs of A. pomi. A 2 per cent solution of 

 crude carbolic acid (Expt. 36, and 37, Table I and Expt. 19-p, 20-p, 

 Table II) was applied on the eggs of A . avence and A . pomi at regular 

 intervals. The percentage of kill was not very great in any applica- 

 tion except on March 21 when the acid killed 90 per cent of the eggs 

 of A. avenae and 85 per cent of the eggs of A. pomi. Altogether this 

 season's results with crude carbolic acid show a smaller percentage of 

 kill than in 1918. Crude carbolic acid (2 gm.-98 cc.) was also com- 

 bined with fish-oil soap (paste form) 1 gm.-50 cc. and sprayed on the 

 eggs of A. avence at regular intervals. This combination killed the 

 greatest percentage of eggs on March 21, 97.2 per cent of A. avence 

 and 87 per cent of A. pomi. All applications of this combination 

 before March 21 permitted 22 to 58 per cent of the eggs to hatch. The 

 addition of fish-oil soap helps materially to increase the efficiency of 

 the carbolic acid mixture, yet the results are by no means sufficiently 

 satisfactory for practical use in orchard spraying. It is also probable 

 that a 2 per cent solution of crude carbolic would injure green swollen 

 fruit buds, if one waited until the eggs were most susceptible to 

 sprays. On March 7, 1919, a large number of experiments were con- 

 ducted on the eggs of A. avence with 1 and 2 per cent solutions of crude 

 carbolic acid, cresol U. S. P., phenol c. p., ortho cresol c. p., meta 

 cresol c. p., and para cresol c. p. and the results were similar to those 

 of 1917-1918. Crude carbolic acid was somewhat superior to all. 

 No spray killed over 60 per cent of the eggs. 



Fish-oil soap at the rate of 1 gm.-50 cc. of water was sprayed on 

 the eggs of A. aven<£ on February 10, March 1, March 10 and March 

 21, and the greatest kill, 85 per cent, took place on March 21. The 

 same strength was sprayed on the eggs of A. pomi on March 21, 1919, 

 and it killed 92 per cent. The percentage of kill of the eggs of A. 

 avence with this same strength of soap and applied previous to March 

 21 was 36 to 52 per cent. Fish-oil soap at different strengths was also 

 combined with various sprays (discussed under separate sprays) . 



Linseed and cotton-seed oil at strengths varying from 2 to 8 per 

 «cent of the solution were thoroughly emulsified with laundry soap 



