Miscellaneous. 355 



orchard above mentioned cost a little less than three cents per gal- 

 lon, which is about double the cost of the lime-sulphur spray, but 

 all one had to do to make the oil spray was to fill a 150-gallon tank 

 nearly full of water and pour in 10 gallons of the soluble oil. A 

 few minutes agitation of the mixture resulted in a perfect emulsion. 

 I like to apply these oil sprays, for they spread much better thaa 

 the lime sprays, so one has not to hit every spot of bark the size of 

 a pin head, as you do with the lime-sulphur sprays. 



My first experience with these soluble oils, as given above, 

 where the trees were as badly infested as ever the next autumn, set 

 me to thinking and trying to explain it. A little calculation will 

 easily demonstrate how necessary it is to make a very thorough 

 application of any insecticide for this pest. For example, let us 

 suppose there were 5,000 scales on a tree when it was sprayed, 

 which would not be a very bad infestation for a tree seven or eight 

 years old. I think the spray killed 95 per cent, of them, thus leav- 

 ing only 250 living scales, of which we will say the winter killed 

 one-half, so that there were only 125 living scales to begin breeding 

 in the spring. Let us allow that one-half of these would develop 

 into males. Then the 62 female scales remaining are each capable 

 of giving birth to from 100 to 500 young lice. Call it only 100, and 

 the first crop of young scales would then amount to over 6,000, and 

 remember that there may be at least two more broods during tha 

 season. It will not require much further manipulation of figures 

 to demonstrate how easy it would be for a few scales which survive 

 one thorough spraying, winter conditions, etc., to propagate enough 

 to infest a tree more seriously than when it was sprayed. These 

 facts demonstrated to me the necessity of making more than one 

 application of any spray in order to reduce the numbers of this pest 

 below the danger limit. I believe we have to kill more than 95 per 

 cent, of the scales, and I doubt if it is often possible to do this in 

 one application of any spray. Therefore, I am recommending tbat 

 the trees be sprayed once in the autumn and once in the early 

 spring before growth begins. I think the autumn spraying is very 

 important, for immense numbers of young and tender scales can 

 then be easily killed, and further development of the insect stopped. 

 I would begin spraying just as soon as the leaves are off. 



Prof. M. V. Slingerland, Ithaca, N. Y. 



— Rural New Yorker. 



