Studies on Eggs of Apple Plant Lice 53 



consisted chiefly of the three isomeric eresols and possibly some 

 xylenol and higher liomolognes. The crude form used in the fol- 

 lowing- experiments may have also contained some phenol. No 

 quantitative tests were made of this acid, but the extensive ex- 

 periments conducted with pure phenols and with all three isomeric 

 eresols during 1918 show the relative value of each constituent of 

 r-rude carbolic acid in respect to killing aphid eggs. The cnulc 

 carbolic acid at varying strengths, 0.5, 1, 2, 5 and 10 per cent, was 

 used in experiments G-4(3 to (J-ol and 0-52 to 0-58 (table 4) and in 

 all cases a small (j[nantity -of soap was used as a spreader. These 

 experiments show an increase in the efl'ectiveness of the spray as the 

 strengths of the acid was increased. Strengths less than 2 per cent 

 acid did Dot kill a sufficient number of eggs to be considered effec- 

 tive, while strengths greater tlian 2 ])er cent acid killed all eggs, 

 and a 2 per cent acid spray killed 9() to 100 per cent. Some experi- 

 im^nts where a small amount of fish-oil soap was used as a spreader 

 also were tried witli var\'ing strengths of crude carbolic acid, and 

 the results obtained were similar to the foregoing experiments. 



In combining crude carbolic acid with soap solutions, it was 

 noted that the crude acid mixes more readily with a fish-oil soap 

 solution than with a laundry soap ("Fels Naptha") solution, and 

 also Avhen thoroughly mixed with a fish-oil soap solution it will 

 remain constant throughout for a considerable period. In preparing 

 mixtures of crude carbolic acid and soap solutions it was advan- 

 tageous to mix the acid thoroughly with two or three times its 

 volume of soapy water, and then make the desired dilution. Fish- 

 oil soap is also superior to laundry soap in that it has greater 

 insecticidal properties. 



The results of the experiments for 1917 indicated that it would 

 be worth while to make a similar but more extensive study of the 

 various isomeric eresols and phenol which go to imake crude 

 carbolic acid and note the effect of each on the eggs of aphides. 

 This was undertaken during the past season, with crude carbolic 

 acid, eresols and phenol at varying strengths and in combinations 

 with different strengths of fish-oil soap, such as solid fish-oil soap, 

 liquid fish-oil soap and resin fish-oil soap. 



In the first place, a number of experiments were conducted 

 from December 15 to March 25, 1918, with a 1 per cent solution 

 (1 part to 99 of soapy water) of crude carbolic acid, phenol c. p., 

 cresol U. S. P., meta cresol c. p., ortho cresol c. p., and para cresol 

 c. p.; laundry soap ("Fels Naptha") being used at the rate of 

 1 gm. to 200 cc. The purpose of these experiments was to de- 

 termine the relative killing effect of the various acids on the eggs 

 of A. avence. The experiments show that the soap solution alone 

 had little or no effect upon eggs, for the percentage of hatch in the 



