xxxii Remedial Measures and Insecticides. 



Whale-oil soaps are found to be the best for the purpose. In 

 Insect Life, vol. vii. p. 369, the following conclusions are drawn 

 from numerous experiments upon trees infested with the San Jose 

 scale {Aspidiotus perniciosiis) in America : — ' Soap washes, par- 

 ticularly of whale-oil soap, have yielded the most satisfactory 

 results ; and at the rate of two pounds to the gallon, under the 

 conditions of thorough drenching of the entire plant, with five or 

 six days of subsequent fair weather, will destroy all the scales, 

 whether applied in fall or in spring. The results with soap in less 

 strength indicate that under the most favourable conditions the 

 same result may be reached with mixtures containing only a pound 

 and a half or more of soap. The action of the soap at the rate of 

 one pound or more to the gallon, applied in the fall, is generally 

 to prevent blooming and fruiting the following spring, but the 

 vigour and healthfulness of the tree are greatly increased. Applied 

 in spring at the time of blooming, it does not injure the plant nor 

 affect the setting of the fruit to any material extent in the case of 

 the peach, and not at all in the case of the apple. 



' The experiments, as a whole, indicate the vastly superior 

 merit of the soap wash and its fall application. The greater vigour 

 of the plant resulting from the fall treatment more than offsets 

 the possible failing of bloom. Owing to the impossibility of con- 

 trolling weather conditions, and the practical difficulty of wetting 

 every part of the plant, one spraying cannot often be relied on to 

 accomplish the death of all the scales, but two conscientious 

 drenchings may be expected to accomplish this result. These 

 may be (i) at the time of, or shortly after, the falling of the foliage 

 in autumn, and (2) just before blooming in spring.' 



Other soaps {hard laundry soap) are eflficacious, but not to the 

 same degree. 



In another of the American reports* is an instructive paper on 

 insecticide soaps, by Mr. C. L. Marlatt, from which I take the 

 liberty of quoting largely : — ' The decided insecticide value of the 

 so-called whale-oil (more properly fish oil) soaps, against scale 

 insects particularly, has been fully demonstrated in the last few 

 years in the work against the San Jose scale, and has fully sub- 

 stantiated Professor Cornstock's early recommendation of this 

 means of controlling scale-insect pests. The merit of these soaps 



* Bulletin, No. 6 (New Series), U.S. Department of Agriculture (Division 

 of Entomology). 



