70 



received very different treatment. Some, for example, were watered 

 but once, and that the next day after the application of the insecti- 

 cide wash; and others were watered daily for the seven days next 

 following- it. In order to avoid interference with the experiments 

 by rains, which fell three times during- the fortnight covered by 

 the greater part of the experiments, some of the trees were covered 

 by canvas tents at night and whenever rain threatened. 



General Statement of Results. 



Details of all forms and variations of the experiment will be 

 g-iven further on, but it is sufficient for this general statement to 

 say that the g-eneral averag-e result of a single spraying- of twenty 

 trees with lime, sulphur, and salt, as tested at the end of a week 

 from treatment, was the destruction of 89 per cent of the scales 

 when no water was applied within five days, and of 86 per cent, 

 when water was used. The corresponding result of the application 

 of lime, sulphur, and blue vitriol to fifteen trees was the destruction 

 of 91.2 per cent, of the scales without water, and 90.7 per cent, when 

 water was applied within the first five days. This statement, how- 

 ever, does not represent the final results of the experiment, for on 

 May 12, ten weeks after the trees were sprayed, an average of 99.2 

 per cent, of the scales alive in the beginning were dead, and there 

 was no perceptible difference in this respect between the lots 

 treated with the Oregon wash and those treated with the Cali- 

 fornia wash, or between those which had simply received the in- 

 secticide spray and those which had been subsequently sprayed 

 profusely with water. 



Still more conclusive and convincing is the statement of the 

 result of an inspection of these trees made August 20, at which 

 time 13,300 scales were examined on 23 of the trees used in the ex- 

 periment, and of this number only twenty-five scales were alive. 

 These living- scales were, in fact, found only on two trees which stood 

 close to an infested hedge which had never received any insecti- 

 cide treatment, and they were only on the branches of these trees 

 next the hedge and interlacing with it. It is scarcely too much to 

 say, consequent!}^, that the apparent final result was practically a 

 complete extermination of the scale on all trees treated. 



Period and Methods of the Experiments. 

 The experiments on which the above statement rests may be 

 conveniently described in five lots: two with lime, sulphur, and 

 blue vitriol; two with lime, sulphur, and salt; and one, a special ex- 

 periment, with both these washes on trees covered by tents. Two 



