50 Bulletin 332 



to 0-44, table 4) at the rate of 1-100, 1-250 and 1-500, and laundry 

 soap (1 gni. to 200 cc.) was used as a spreader. The percentages 

 of hatcli in the check and in the experiment where the laundry soap 

 was tried alone were approximately the same, 40 per cent and 39.2 

 per cent, respectively; consequently the soap must have had very 

 little effect on the percentage of hatch when combined with the 

 nicotine. The percentage of hatched eggs was reduced in all the 

 experiments with the nicotine. AVhere the nicotine was used at 

 the rate of 1-500 the percentage of hatch was 22.4 per cent, or 

 17.6 per cent loAver than in the check. The greater strengths of 

 nicotine showed a still greater reduction. According to the above 

 experiment with "Black-leaf 40" 1-500, when combined with 

 enough laundry soap to act as a spreader, the reduction in the 

 number of hatched eggs is not sufficient to warrant the use of the 

 same as a control measure. Greater strengths than 1-500 are pro- 

 hibitive on account of the cost. 



During the dormant season of 1917-18 a number of experiments 

 were conducted with ''Black-leaf 40" combined with lime-sulfur 

 1-9, fish-oil soap and resin fish-oil soap. In all but one or two of 

 these experiments the combined spray was considerably more ef- 

 fective than the lime-sulfur, fish-oil soap, or resin fish-oil soap alone. 

 This was particularly true when the combined spray was applied 

 near the time when the nymph emerges, or in other words, when 

 the greatest number of eggs show a split outer shell. The superi- 

 ority of a combined nicotine and lime-sulfur spray over lime-sulfur 

 alone has been considered under the discussion on lime-sulfur. 



The experiments with the combinations of "Black-leaf 40", 

 and fish-oil soap sprays made from solid soap show the greatest 

 percentage of kill, 100 per cent, where the "Black-leaf 40" 1-500 

 was combined with fish-oil soap, 1 gm. to 50 cc. (= 1 pound to 6 

 gallons), or 1 gm. to 25 cc. (^ 1 pound to 3 gallons), and sprayed 

 on the eggs of A. avence as they started to emerge, March 22. 

 Fish-oil soap alone at the same respective strengths and applied 

 on the same day killed only 85 and 92 per cent of the eggs. A 

 comparison of the results in the two tables (11 and 13) shows the 

 relative .superiority of a combined spray of nicotine and fish-oil 

 soap over fish-oil soap alone. 



A num])er of experiments were conducted also with nicotine com- 

 bined with fish-oil soap sprays made from liquid fish-oil soap, and 

 with similar concentrations (by weight) the percentage of kill was 

 not as great as with fish-oil soap made from solid soap. This is 

 undoubtedly due to the fact that commercial liquid fish-oil soap 

 possesses a considerable portion of water (60-70 per cent) ; conse- 

 quently, there is not as much soap present when diluted to the 

 desired strength. 



