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ploy artificial means in order to rid the trees of these pests. For this 

 purpose the treatment with hydrocyanic- acid gas and the resin wash, 

 both of which are referred to above in the articles treating of the Eed 

 Scale, are also employed for the purpose of destroying the Black Scale. 

 The gas treatment proves fatal to the scales, but does not destroy all 

 of the eggs. The resin wash destroys the greater number of the eggs 

 and also of the younger scales that it reaches, but it does not always 

 destroy the larger individuals. On the 6th of November, 1890, I had 

 eleven olive trees sprayed with the resin wash made according to the 

 following formula : 



Resin pounds.. 18 



Caustic soda (70 per cent strong) do 5 



Fish oil - pints.. 2£ 



Water, sufficient to make gallons . . 100 



The Black Scales infesting these trees were less than one-third grown. 

 I examined them on the 13th of December, and found that nearly all 

 of the scales were dead, those still alive having to all appearance es- 

 caped being sprayed with the wash; the leaves and fruit upon these 

 trees had not in the least been injured by the wash. 



On the 22dof September of the above-named year I sprayed a small 

 olive tree with a wash made in accordance with the above formula, and 

 after carefully examining the Black Scales upon it on the 21st of the 

 following month I found only a single living scale, while the leaves on 

 the tree were uninjured. On the 6th of January of the present year I 

 was shown an Abutilon plant thickly infested with Black Scales, and 

 was informed that it had been quite recently sprayed with a wash 

 practical 1 y the same as that described above; still quite a large per- 

 centage of the oldest scales had not been destroyed by the wash. It 

 would therefore be advisable to spray the trees at a time when the 

 scales are very young; this period in ordinary seasons extends from 

 about the first of October to the beginning of the new year. 



In place of the above wash, some of our fruit growers use one which 

 contains no fish oil, being composed simply of resin, caustic soda, and 

 water. This, besides being cheaper than the preceding wash, is also 

 less troublesome to make, and while it is not so effectual as the former 

 wash, still it proves fatal to a large percentage of the younger Black 

 Scales. One of my correspondents, Mr. 0. B. Messenger, of Pomona, 

 in a letter to me bearing date of March 31, 1890, gives his experience 

 with a wash of this kind as follows : 



Last year some of the trees I sprayed in midsummer with a wash consisting of resin, 

 25 pounds; caustic soda, 6 pounds, in 100 gallons of the wash, were almost perfectly 

 cleaned of Black Scales, hut I now find that the fruit, or rather a small portion of it, 

 was made unsalable by the solution giving the oranges a russety appearance. Some- 

 times the whole orange is thus affected, but usually only in streaks where the solu- 

 tion collected and ran around to the under side, where it was the worst. The spray- 

 ing did not act in the same way on the fruit in the other orchards, although the 

 same strength of wash was used throughout the season. The present work was fol- 

 lowed by very hot weather. Was this the cause of it f 



