THE CITRUS THRIPS. 29 
CONTROL EXPERIMENTS. 
PLAN OF SPRAYING EXPERIMENTS IN 1911. 
The principal experiments in 1911 were conducted in an orange 
orchard about 2 miles east of Lindsay, Cal., and about the same dis- 
tance from the nearest foothills, lying between the latter and the 
town. A supplementary set of experiments was conducted in an 
orchard situated on the slope of the foothills about 2 miles from 
the first orchard, the object being to test out practically the same 
sprays under different conditions. The trees of the latter orchard 
were younger than those of the former, and, as is true of most foot- 
hill groves, worse thrips infested. The insecticides used in the two 
sets of experiments are listed below, Series I referring to the valley 
orchard and Series II to the foothills orchard. A further experi- 
ment, in which 2,550 Valencia and Joppa and a number of navel 
nursery trees were sprayed, was conducted in a third orchard about 
2 miles from the foothills. 
Series I: Valley ranch. 
Plat No. 1. Unsprayed, check. 
2. Lime-sulphur solution (36° Bauuie), 1-28. 
3. Lime-sulphur solution (36° Baume), 1-56. 
4. Unsprayed, check. 
5. Tobacco extract (40 per cent nicotine sulphate), 1-800. 
6. Tobacco extract (40 per cent nicotine sulphate), 1-1,600. 
7. Unsprayed, check 
8. Lime-sulphur solution (36° Baume), 1-86, and tobacco extract 
(40 per cent nicotine sulphate), 1-800. 
9. Lime-sulphur solution (36° Baume), 1-86, and tobacco extract 
(40 per cent nicotine sulphate), 1-1,600. 
10. Lime-sulphur solution (36° Baume), 1-86, and tobacco extract 
(40 per cent nicotine sulphate), 1-2,400. 
11. Cresol soap, 1-500, and tobacco extract (40 per cent nicotine 
sulphate), 1-800. 
12. Cresol soap, 1-500, and tobacco extract (40 per cent nicotine 
sulphate), 1-1,600. 
13. Unsprayed, check. 
14. Fish-oil soap, 1-250, and tobacco extract (40 per cent nicotine 
sulphate), 1-800. 
15. Fish-oil soap, 1-250, and tobacco extract (40 per cent nicotine 
sulphate), 1-1,600. 
16. Sulphur-soda solution, 1 1-25. 
x The sulphur-soda solution (plats 16 and 17) was prepared as follows: 
Powdered sulphur pounds— 30 
Powdered caustic soda (98 per cent) do 15 
Water to make gallons— 30 
The sulphur was made into a paste with water and the soda added, while the mixture 
was constantly stirred, in sufficient quantity to cause boiling, a little water being added 
occasionally to retard the cooking. When all the sulphur was dissolved, enough cold 
water was added to make a stock solution of 30 gallons. A clear, amber liquid, much 
resembling good lime-sulphur, was the result. 
