PESTS OF THE nop citop 125 



gallons of water and six pounds of broken resin, to be 

 boiled with about three (jiiarts of the resultant lye. 

 After the resin is dissolved, the rest of the lye is to be 

 added slowly, with water to make abinit eii;ht L^'ailons of 

 the eompound, whieh should be still furtherchlutedwith 

 water before eoolint;'. The resulting mixture should 

 be clear and brown in color, and at this stage it is read- 

 ily diluted with water. Improvements liave been 

 made since i8o3 ^vith the wash and the formula now 

 recommended l)y the writer's office is as follows: Resin, 

 20 pounds; crude caustic soda (78 per cent.) 5 ])ounds; 

 fish oil, 2j pints; water to make 100 gallons. Ordinary 

 commercial resin is used, and the caustic soda is that 



FIG. 62. CYNIPID PARASITE OF HOP PLANT LOUSE. 

 Greatly enlarged. (From U. S. Department of Agriculture.) 



put Up for soap establishments in large 200-pound 

 drums. Smaller quantities may be obtained at soap 

 factories, or the granulated caustic soda (98 per cent.) 

 used — 3J pounds of the latter being equivalent to five 

 pounds of the former. Place these substances, with 

 the oil, in a kettle with water to cover them to a depth 

 of three or four inches. IJoil about two hours, making 

 occasional additions of water, or until the compound 

 resembles very strong, black coffee. Dilute to one- 

 third the final bulk with hot water, or with cold water 

 added slowly over the fire, making a stock mixture 

 to be diluted to the full amount as used. When 

 sprayed the mixture should be perfectly fluid, 



