23 



kind of insecticide, and they certainly gave no evidence of snch treat- 

 ment. The dead scales showed no indications of having been destroyed 

 by ladybirds nor yet by internal parasites. Wishing to ascertain if 

 this singular mortality was general among these scales in other locali- 

 ties, I examined several infested pear trees in this city, but found that 

 the fruit and new growth upon them were thickly infested with these 

 scales, which were alive and to all appearance in a very thriving con- 

 dition. It would appear, therefore, that this mortality among the San 

 Jose Scales was entirely due to certain climatic influences, unless it 

 can be shown to have been due to some low form of fungus growth. 



The remedy most extensively used in this State for the destruction 

 of the San Jose Scale on dormant trees is the one containing lime, salt, 

 and sulphur, described in my annual report to Prof. Riley for the year 

 1890 and published in Bulletin No. 23, Division of Entomology, of this 

 Department (pp. 30 to 34). I there gave an account of a series of ex- 

 periments which I had made with the above mentioned substances, 

 both when used siugly and also when used in various combinations, 

 and expressed my intention of pursuing this subject still further the 

 following winter with a view of improving upon the insecticidal proper- 

 ties of the wash used at that time. Accordingly, on the 10th of Feb- 

 ruary, 1891, I made a number of experiments with the above-mentioned 

 ingredients, and give herewith a brief account of the principal ones : 



Experiment 260. — Sulphur, 30 pounds; lime, 43 pounds; water sufficient to make 

 100 gallons. The sulphur and lime were placed in the kettle together and water 

 added; the whole was then boiled for two hours without first allowing the lime to 

 slake; the solution did not assume an orange-yellow color as soon as in other experi- 

 ments where the lime was first slaked before being boiled with the sulphur. Strained 

 the solution and sprayed two pear trees with it at about 2:20 p. m. ; sun shining; 

 light breeze. Examined these trees March 26 and found a great many living San 

 Jose Scales upon them. 



Experiment 261. — Same as in the preceding experiment, except that before spray- 

 ing it upon the trees I added 23 pounds of salt to the diluted solution and stirred it 

 until the salt was dissolved, then sprayed a peach tree with it at about 2 o'clock in 

 the afternoon. Examined this tree March 25 and found upon it many living San 

 Jose" Scales. Still, these were not as numerous as upon the trees treated in the pre- 

 ceding experiment, where no salt had been used. 



Experiment 258. — Sulphur, 45 pounds ; lime, 65 pounds, water sufficient to make 100 

 gallons. The sulphur and lime were first placed in the kettle; water was then added 

 and the lime allowed to slake, after which more water was added and the whole then 

 boiled for two hours. At first the solution was of a pale yellow color, but it soon 

 became dark orange yellow, assuming this color much sooner than was the case in 

 experiment 260, where the lime was covered with water and boiled without first be- 

 ing allowed to slake. The solution when properly diluted was strained and two 

 apple trees were sprayed with it at about 2:40 p. m. 1 examined these trees March 

 26, and found quite a large number of living San Jose" Scales upon them. 



Experiment ^5#.-^Same as in 258 except that when diluted ready for use I added 31 

 pouuds of salt to the solution and stirred it until dissolved, then sprayed a prune 

 tree with it at 3 o'clock in the afternoon. I examined this tree March 26 and found 

 a few living San Jose* Scales upon it, much less than in experiment 258, or any of 

 the preceding ones. 



