Studies on Eggs of Apple Plamt Lice 57 



known. The greatest strength, 1.5 per cent, of the three was the 

 most effective. Furthermore, whenever the same strength of one 

 acid was used with the two dift'erent strengths of hsh-oil soap the 

 greatest percentage of kill took place when the stronger fish-oil soap, 

 ] gm. to 50 cc, was used. 



If all the above facts are consistent throughout then the one 

 experiment where crude carbolic acid composed 1.5 per cent of the 

 spray combined with a fish-oil soap solution, 1 gm. to 50 cc, and 

 applied on March 28, should show the smallest percentage of hatch. 

 This is the actual case, for the experiment, which fulfills the above 

 requirements, is the only one in the entire lot which shows no hatch, 

 or 100 per cent kill. All other experiments showed some hatch. If 

 the above requirements were fulfilled in orchard spraying it would 

 be possible to control the aphis with this spray. These experiments 

 and others not shown in this paper indicate that a 2 per cent 

 solution of crude carbolic acid combined with a strong fish-oil soap 

 solution would come nearer to controlling aphides in the stage than 

 a 1 or 1.5 per cent acid solution. 



A somewhat similar series of experiments (not shown in the 

 table form) were conducted with cnide carbolic acid, cresol U. S. P., 

 and phenol c. p., combined with fish-oil soap solution which had been 

 made from liquid fish-oil soap. In these experiments the effective- 

 ness of the combination between the acid and the fish-oil soap was 

 decreased as the strength of the fish-oil soap was increased. This 

 apparent inconsistency was prol)ably due to the fact that the liquid 

 fish-oil soap is strongly basic, and this basic condition of the soap 

 neutralized the acid as its strengtlr was increased. 



Similar combinations between the three acids and resin fish-oil 

 soap were tried, but these were not extensive enough to warrant a 

 conclusive statement concerning their effectiveness. A comparison 

 of these results witli com])inations of the acids and fish-oil soap 

 solutions uuide from solid fish-oil soap showed that the effectiveness 

 of the combinations between the acids and the resin fish-oil soap 

 was somewhat less than when the acids were combined with fish-oil 

 soap solutions made from solid soaji. 



The effect of crude carbolic acid on various fruit trees during 

 the dormant season has never been determined, so far as is known ; 

 consequently it was necessary to conduct some preliminary experi- 

 ments along this line. Six apple trees were experimented on, one 

 old tree and five 6-year-old trees. On April 2, 1917, two of the 

 6-year-old trees and a portion of the mature tree were sprayed with 

 a 2 per cent solution of crude carbolic acid plus laundry soap at 

 the rate of 1 pound to 24 gallons of water. During the same day 

 two 6-year-old trees were sprayed with a 5 per cent solution of 

 crude carbolic acid with laundry soap as a spreader. One 6-year- 



