380 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



moisture and temperature were controlled and also out-of-door obser- 

 vations during variable seasons show that high evaporating factors 

 during the most susceptible period of the egg (10 to 15 days before 

 hatching) decreases the percentage of hatched eggs while low evaporat- 

 ing factors during the same period increases the percentages of hatch. 



The eggs are not only most susceptible to evaporating factors when 

 many of the eggs are splitting their outer shells, but they are most 

 easily killed by various contact sprays applied at this time. Exper- 

 iments with a large number of contact sprays at their recommended 

 winter strength shows conclusively that concentrated liquid lime- 

 sulfur, 1-9 is the most efficient. The lower efficiency of recommended 

 winter strengths of dry lime-sulfur and substitutes is probably in part 

 due to the lower sulfur content of each. The insoluble character of 

 dry lime-sulfur is also important in accounting for its inefficiency. 



Nicotine added to any spray increases its efficiency in killing the 

 eggs of A . avenoe and A . ponii. This was particularly true where nico- 

 tine, 1-500 is added to the recommended dormant strengths of con- 

 centrated liquid lime-sulfur, dry lime-sulfur and substitutes ("B. T. 

 S." and ''Soluble Sulphur"). 



Sodium sulfo-carbonate, 1-9 or 1-14 kills a large percentage of eggs 

 and is worthy of further investigation. Various sprays made with 

 hydrated lime, strong fish-oil soap solutions, miscible oil ("Scalecide," 

 1-15 to 1-40), crude carbolic acid, cresols, linseed and cotton-seed oil 

 emulsions, etc., only kill a small percentage of eggs during December, 

 January, February and the early part of March. Some of these sprays 

 kill 80 to 95 per cent of the eggs if applied when the fruit buds first 

 show green (March 21, 1919). 



The New Jersey Agricultural Experiment Station is recommending 

 a delayed dormant spray of concentrated liquid lime-sulfur, 1-9, com- 

 bined with nicotine (Black Leaf 40), 1-500. This spray should be 

 apphed when the fruit bud is swollen and first shows green. Apphca- 

 tions made after the leaves are out one half inch or more will burn the 

 foliage of most varieties. 



