REPORT OX VARIOUS METHODS FOR DESTROYING THE 

 RED SCALE OF CALIFORNIA. 



By D. W. Coquillett, Special Agent. 



LETTER OF TRANSMITTAL. 



Los Angeles, Cal., October 30, 1889. 



Sir : I herewith submit my annual report on some of the results obtained by me 

 during the past year. 



During the first half of the year nearly my whole time was occupied in propagat- 

 ing and distributing the Lady-birds (Yedalia cardinalis Mulsant) recently imported 

 from Australia by this Division. So thoroughly have these insects destroyed the 

 Fluted or Cottony-cushion Scale (Icerya purchasi Maskell) that at the present time it 

 is difficult to find a living specimen in any portion of the southern part of this State. 

 From the 129 Lady-birds received from the 30th of November to the 24th of January 

 and colonized under a tent covering an orange tree in this city, by the following mid- 

 summer I had, with the help of Mr. J. W. Wolfskill and Mr. Alexander Craw, dis- 

 tributed nearly 15,000 of these insects to various parts of the State, which will give 

 some idea of the great fecundity of these insects. My first attempt at colonizing 

 them on trees in the open air was made in the 35-acre orange grove belonging to Col. 

 J. R. Dobbins, and located in the San Gabriel Valley in this county. I colonized 35 

 of the Lady-birds on one of the trees February 22 and about 100 more on the 20th of 

 March, and Colonel Dobbins writes me that they had practically freed his grove of 

 the Iceryas by the 31st of July. 



The large Chapman orange-grove, also located in the San Gabriel Valley, and com- 

 prising 150 acres of citrus trees, has likewise been practically cleared of the Iceryas 

 by these Lady-birds, the first colouy of which I placed in this grove on the 20th of 

 March. As might naturally be expected, this freeing of the orange-groves from one 

 of the greatest pests with which they were ever infested removes a great burden 

 from the shoulders of our orange-growers ; or, as one of them, Mr. A. Scott Chapman, 

 writes to me: " They have taken more than an oppressive burden off of the orange- 

 growers 7 hands, and I, for one, very much thank the Division of Entomology for the 

 Vedalia cardinalis — the insect that has worked a miracle." 



One of the most important results obtained by me the past season has been the dis- 

 covery of a method whereby trees could be treated with hydrocyanic acid gas at a 

 price scarcely exceeding one-third of what it has heretofore cost by the old method. 

 As the great expense attending the use of this gas has been the one great objection 

 to its being universally employed for the destruction of scale-insects infesting trees, 

 this objection having been now overcome we may naturally expect to see this 

 method coming into more extended use than has been the case heretofore. As I have 



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