48 Bulletin 332 



eggs of apple aphides, consequently a large number of experiments 

 were conducted with varying concentrations of fish-oil soap spraj's 

 (made from solid and liquid soaps) and resin fish-oil soap on the 

 eggs of A. avence out-of-doors at the laboratory during February 

 and IMarch, 1918. The results of these experiments are given in the 

 usual manner in tables 11 and 12. 



These experiments recorded in table 11 and others of a similar 

 nature show that fish-oil soap sprays made from either the solid 

 or li(iuid form are quite effective in killing aphid eggs. Similar 

 concentrations of laundry soap are not as effective as the fish-oil 

 soaps. Comparing the effectiveness of the same concentration of 

 fish-oil soaj) sprays made from solid and liquid fish-oil soap, the 

 percentage of hatch was much less where the fish-oil soap spray 

 was made from solid fish-oil soap.^ 



Resin fish-oil soap (table 12) was also given a thorough trial 

 in a set of experiments similar to the above, and the results of the 

 experiments show that resin fish-oil soap is not as effective in killing 

 eggs as the same concentration (by weight) of fish-oil soap sprays 

 made from solid fish-oil soap. The lowest percentage of hatch 

 with resin fish-oil soap, 1 gm. to 25 cc, applied on March 22, was 

 14.8 per cent, while a similar concentration of fish-oil soap made 

 from solid soap reduced the percentage of hatch to 7.2 per cent 

 when applied on the same day. 



All the series of experiments (soap of same concentration) 

 with the various soaps show the greatest percentage of kill or the 

 smallest percentage of hatch when the spray was applied near the 

 time when the nymph emerges. In other words, the exposed pig- 

 mented layer of the eggs is more pervious to soap solutions than 

 the outer tough layer. This observation again substantiates a 

 former statement made in discussing contact insecticides; Avhen the 

 greatest number of eggs show a split-out shell, then the greatest 

 number of eggs will be most susceptible to various contact insecti- 

 cides. The greatest number of eggs with a split outer covering 

 occurs at the time when the first nymphs emerge. 



Nicotine 



A number of experiments have been conducted with nicotine 

 as found in the commercial products called "Black-leaf 40" and 

 "Nicotine resinate" (40 per cent nicotine in each). These are 

 manufactured by the Kentucky Tobacco Products Company. Louis- 

 ville, Ky. In 1917 the "Black-leaf 40" was applied on the eggs 

 of A. avenie out-of-doors at the laboratory on April 3 (exp. 0-41 



2The solid and liquid fish-oil soaps were purchased from Capstone 

 Manufacturing Co., Newark, N. J., and the resin fish-oil soap from 

 James Good, Philadelphia, Pa. 



