PROCEEDINGS OF THIRTY-THIRD FRUIT-GROWERS' CONVENTION. 171 



tree and fruit by fumigation. The latter process is now in almost 

 universal use throughout the orchards of the south and betterment of 

 fruit and trees has been most marked. 



Fumigation, however, is still far from an exact science and results 

 are not so uniform as they should be, depending largely upon the 

 degree of intelligence and reliability of the operators. 



A new significance has been given to the use of cyanide fumigation 

 for insect control, by a practice originating with the Los Angeles County 

 Commissioners of Horticulture and used extensively since that time 

 (November, 1904) for the extermination of the more resistant scales, 

 like the purple and the red scales. Up to that date these two pests had 

 been fought with all sorts of applications for a period of at least sixteen 

 years, without a single instance of entire eradication, so that the saying 

 passed into a proverb that "once red scale always red scale," and the 

 purple scale, though not so well known, came to be considered in the 

 same class. It had become the common practice to treat these scales 

 by repeated fumigations, at intervals of about two months, with the 

 dosage commonly used for black scale, proceeding upon the theory that 

 the successive broods of young while yet in their tender stages could 

 thus be killed and finally total eradication take place. This method 

 proved to be exceedingly expensive, prohibiting all profit from the 

 infested grove, and continued the nuisance indefinitely. Any one 

 familiar with these scales knows that they have no well-defined periods 

 of breeding, at least none which involve the whole mass of the infesta- 

 tion, but that these masses consist of all sizes and conditions of scale, 

 some portions of which will be an egg-forming stage at almost any given 

 time. In the case of the purple scale these eggs are not killed by 

 ordinary cyanide dosage, but hatch out later to reinfest the tree, while 

 in the case of the Asp-idiot us scales (which do not produce their young 

 from eggs, properly speaking) there are at any given time mature 

 specimens in any considerable infestation which have passed the stage 

 when this light dosage will kill them, and these will reproduce their 

 successors after the treatment of the tree. With this view of the subject 

 in mind, it was conceived that any process of treatment for these 

 resistant pests which offered any hopes of their eradication must be 

 effectual in destroying, at one time, the entire infestation, including the . 

 eggs, in the case of the Lecaniums. 



Increased dosage and lengthened exposure by the cyanide process 

 have proven the easy solution of the problem, and it only remains for 

 the fumigators to become proficient in the use of this heavy dosage to 

 bring it into general use, nor is this proficiency difficult to acquire. 

 The universal belief that the limit of safety had been reached (or 

 nearly so) in the so-called full or killing dosage used for black scale,, 

 and that any material increase of the chemicals must destroy or greatly 



