558 REPORT OP THE COMMISSIONER OF AGRICULTURE. 



KEPOET UPON SUPPLEMENTAEY EXPERIMENTS ON THE COTTONY 

 CUSHION-SCALE ; FOLLOWED BY A REPORT ON EXPERIMENTS 

 ON THE RED SCALE. 



By Albkrt Koebele, Special Agent 



LETTER OP TRANSMITTAL. 



Alameda, Cal., December 1, 1886. 

 Sir : I bci-ewitli submit a report of continued experiments on the Cottony Cushion- 

 scale {Icerya purchasi), made at Los Angeles, Cat., after the expiration of the ap- 

 pointment of D. AV. CoquUlett, with whom I worked previously, as directed by you 

 in letter of January 28. 



ily warmest thanks are due to Mr. Avigust Buschhaupt, of the Los Angeles Soap 

 Company, for kindly assisting me in preparing the various soaps. 

 Very respectfully, 



ALBERT KOEBELE. 

 Prof. C. V. Riley, 



U. S. Entomologist, Washington, D. C. 



INTRODUCTOKY. 



The chief object of my work has been to find a wash as low in price as possible, 

 and at the same time one which all the f ruit-growei-s can prepare themselves. This, 

 as is shown below, is not a difliciilt matter. 



In March and April, while at work with Mr. CoquUlatt, and after witnessing vari- 

 ous experiments, especially with soaps, I concluded that those, if tried in all their 

 varieties, would prove good agents in destroying the scales, and that they also could 

 be produced at a very reasonable cost. Up to this day, in nay limited intercourse 

 with orange-growers, I have seen nothing cheaper for kilUng the Cottony Cusliion- 

 scale. 



It has always been a difficult matter to know just how much of the article used 

 should be taken to a certain quantity of water to be efTective on the scales and not 

 injure the trees. Very often the spi'aymg is done by inexperienced hands, and in 

 such cases no good results can ever be expected even with the best washes. Natu- 

 rally it will be used in stronger doses at the next operation, and the consequence 

 will often be that there is more injury done than good. Experienced hands shoidd 

 always be engaged in this work to secure good results. I have myself witnessed a 

 pair of inexpert operators, and was much amazed at the rapid progress of the work; 

 yet when examining the trees a week later it was hard to tind *' dead scales." 



No wash will be effective on Icerya unless penetrating the cottony mass, and for 

 this purpose I found soap, or washes of soapy nature, the best. In most cases the 

 majority of the young scales are found among the egg-masses, and unless these are 

 destroyed the labor is of little value. 



SOAP SOLUTIONS. 



Almost any soap, if used in right quantity, will be destructive to both the eggs 

 and the insects of Icerya, and, aside from resin compounds, will best penetrate the 

 cottony mass. The egg-masses should always, and immediately after the tree lias 

 been sprayed, bo completely penetrated by the Avash. Unless this is the case the 

 wash has not the effect of destroying everything. In some of the washes used, 

 especially such as contained resin, the egg-masses, if not reached in the center, be- 

 came so hard that rarely one of the young scales was able to leave its place of birth. 

 Often one or more newly hatched scales will be found under the body of tlie motiier 

 scale at the point where the beak is inserted. Here, too, the mother scale exudes a 

 httle of the cottony substance, on which the body rests close to the bark. After light 

 spraying and with weak wash this place remains dry and the young scales unin- 

 jured. Therefore a strong spray is of value, by which the scale is raised or some- 

 Avhat removed from its firm place. Soaps 144 and 153, which I have made, will do 

 as well at i cent with a strong and tiiorough spraying as at i cent by weak spray. 

 Never have I observed eggs that were completely Avetted by any of the washes used 

 to hatch; in every instance they A^-ere destroyed. 



For apiilying solutions there is nothing better than a cyclone nozzle for thorough 

 work, especially if the exit hole be made considerably larger, to saA'e time, and tlus 

 is easily done. 



The cyclone nozzle used in my experiments had been eaten out opposite the exit 



