THE PEAR THRIPS AND ITS CONTROL. 65 
An effort should be made to kill all adults in an orchard before 
March 15, when practically all thrips are out of the ground and when 
oviposition begins. 
The black-leaf tobacco extract may be purchased from local agents. 
The distillate oil emulsion can also be purchased from local dealers 
in spraying supplies, but is prepared after the following formula: 
Hot water. oo each oe se acsie nce ase ese es teas cocina aoe esis gallons.. 12 
Whale-oil or'fishi-cil’soapts 4. eu eee. soe ES pounds.. 30 
Distillate: ob (28> Bam) ett ke eemoals eeseis ees ee gallons.. 20 
The soap is first dissolved in a kettle of boiling water and then 
removed to the spray tank, where the oil is added. This should be 
agitated violently and sprayed out under pressure of from 125 to 150 
pounds into other barrels. This stock solution contains about 55 
per cent of oil, and should be diluted at the rate of about 2 gallons of 
the emulsion to 48 gallons of water for a 2 per cent oil solution. 
The secret of making a thoroughly good stock emulsion lies in 
having the soap and water boiling hot, in adding the oil to this solu- 
tion, and under no circumstances in adding the soap and water to 
the oil, in thorough and violent agitation, and, finally, in passing it 
through the spray nozzles under high pressure. It has been found 
by repeated experiments that high pressure is the most important 
factor, and an emulsion passed once through the pumps and nozzles 
under pressure of from 150: to 160 pounds can not be improved by 
repeating this operation. 
Fish-oil soap may be made as follows: 
VERGE ce Sete Sire oS a Sat oc onape wisi cs 'aioei a ai gallons.. 6 
IKiGieecostacnadae dle sir Mes & ei ep ener tains ely Gr el Relea pounds.. 2 
Bani Gil eee se Oe nee Soars eee eee ees c te eee Shen shh gallons.. 14 
Place the water in a caldron, add the lye, and then the fish oil, 
and boil slowly for about two hours. This will make about 40 pounds 
of soap or about a 5-gallon mixture. 
FERTILIZERS. 
The numerous fertilizers and soil fumigants tested have proved 
ineffectual in killing thrips in the ground, even when applied in pro- 
portions far beyond what could be used in ordinary practice. It is 
evident, however, that most orchards need fertilizers to strengthen 
the buds and to insure a more regular setting of fruit. It has been 
demonstrated repeatedly with other crops that soil soon deteriorates 
unless there is a rotation of crops or unless fertilizers are added. 
IRRIGATION. 
Irrigating for thrips during any time of the year is entirely ineffec- 
tual. Their bodies are so strongly resistant to water that while in 
the ground it is not practicable to submerge them long enough to 
