No. 4.] SCALE INSECTS. 431 



case this seems to have been due to faiUire in proporl}'^ carry- 



inir out the directions for the work. Either the tent or box 



used was not air-tight ; or the potassic cyanide was of the 50 



per cent strength usually sold by druggists, instead of the 



98 per cent or 99 per cent strength necessary ; or the time 



duriiiij: which the fumii»ation was continued was not sufficient. 



Failure to meet any one of these requirements would give a 



failure in the results. 



Spray inc/. 



Of the many materials used for sprajang for the San Jose 

 scale, few are of nuicli value, and none may be expected to 

 destroy all the scales, as some will in all probability fail to be 

 touched. On the thoroughness of the work, then, depends the 

 success of the treatment. 



If but a few trees are to be sprayed, it is probable that 

 potash whale-oil soap will cause the least trouble to apply, 

 At the Hatch Experiment Station at Amherst several brands 

 of this soap were tested in 1902, and the best results were 

 obtained with Bowker's tree soap. Two pounds of this soap 

 were dissolved in each gallon of water used, and the solution 

 was sprayed warm, using an ordinary spray pump and a 

 .Vermorel nozzle with very small opening, giving a fine mist. 

 All parts of trunk and Ihnbs were covered by the spray, 

 treatment of any portion being stopped the moment the 

 spra>' began to drip or run down the bark. 



Crude petroleum and kerosene were also used in the form 

 of a mechanical enudsion with water. This emulsion was 

 produced by the pump (Kerowater), which has two tanks, 

 one for oil and one for water, with a line of hose from each 

 to the nozzle where the two streams combine and are forced 

 out together, the proportion of each being regulated by attach- 

 ments of the pistons to the pump handle. The results with 

 both of these materials were less satisfactory than with whale- 

 oil soap. The strength of oil in the oil-water mixture should 

 have been 20 per cent, but it varied greatly from that, and 

 the whole apparatus was heavy and awkward to handle. As 

 spraying with these materials requires a two-tank pump, it 

 seems not to be the best method of treatment for small 

 orchards or infested areas. 



