58 



favorable it will be efficient; otherwise measurably useless. The cost 

 of the application is very slight, especially if it is prepared in hogs- 

 heads with steam. He said that the surprising results reached by Dr. 

 Forbes were difficult of explanation, especially as rains or artificial 

 washing of sprayed plants did not seem to affect the efficiency in the 

 case of his tests. He believed that the result of Dr. Forbes's work 

 made it necessary for experiment station entomologists everywhere to 

 give the matter again a thorough test in the East, and he proposed 

 that the Division of Entomology in Washington undertake experi- 

 ments next winter with the wash. The chemical analyses which had 

 been made by the Bureau of Chemistry indicated that while the wash 

 would remain in evidence as a white coating on the trees for a lono- 

 time in spite of heavy rains, most of the beneficial elements would 

 soon be leached out. As to the formula for the wash, he stated that 

 it varied with almost every person who experimented with it. The 

 chemical reaction between the sulphur and lime was well known, 

 and if too much lime was used, as was ordinarily the case, it simply 

 remained free lime in the mixture and added to the coating on the 

 trees. The general reactions with the lime, sulphur, and salt were 

 noted in the chemist's report in the publication cited above. 



Referring to the records of percentage of scales killed, he said that 

 in making these estimates it was necessary to take into account the 

 transformations of the scale insects, and that the great majority of the 

 San Jose scales on a tree in late winter would be the male scales. On 

 trees in the orchard in the Department of Agriculture, perhaps 97 

 per cent of the living scales on the trees in April of this year were of 

 the male sex. These hatch out very early in the spring, and when 

 they are gone at once give the appearance of death to a very large 

 percentage of the scales on the trees. He stated also that, where 

 female scales from any cause have not been fertilized by males, their 

 period of life is very greatly increased, so that it is sometimes possible 

 to find overwintered female scales on trees in midsummer. An exam- 

 ination he had made of some of these had indicated that the} T had not 

 been fertilized and were not developing eggs, and they ultimately 

 perished without having reproduced. It thus might happen that all 

 the male scales would be killed, and the female scales would remain 

 unfertilized, though alive, and would perish before a succeeding brood 

 of males would be produced. 



In California the difficulty of spraying large trees was largely 

 reduced Irv having them pruned back vigorously, and it was generally 

 believed that the benefit in the ease of gathering the fruit and the 

 superior quality of the fruit coming from this vigorous pruning offset 

 the cost and trouble of spraying, so that the San Jose scale instead of 

 causing a loss had really worked advantageously to the fruit grower. 

 This applied especial!}- to the peach and prune. 



