THE COMMON MEALYBUG IN CALIFORNIA. 7 



poor in comparison with those tabulated are to be expected under 

 drill or double-filled duck covers. 



Treatment under gas-tight tents is eminently successful from the 

 standpoint of general control, it being possible to secure complete 

 eradication on a small number of trees, and such treatment would 

 be recommended in preference to any other means of artificial 

 control but for the fact that no gas-tight tenting material practical 

 for commercial usage is known at present. It is to be hoped and 

 expected that a suitable gas-tight cloth will be forthcoming in the 

 future. The dosage should be 1 ounce of sodium cyanid to each 100 

 cubic feet of space beneath the tented tree ; for eradication, 1 \ ounces. 



Citrus trees in dormant condition during the winter months will 

 withstand safely a dosage as high as 1J ounces of sodium cyanid to 

 100 cubic feet of space under gas-tight covers. Heavy, repeated 

 dosages under ordinary commercial tents have been used at this time 

 with little damage to the trees. It is unsafe, however, to apply such 

 concentrated gas to orange or grapefruit trees during the growing 

 season. 



Eradication of the mealybug can be effected in a gas-tight box 

 or room with a dosage rate of 1 ounce of sodium cyanid to each 100 

 cubic feet of space. 



SPRAYING. 



RECOMMENDED SPRAY FORMULAS. 



More than 100 different sprays have been tried against the mealy- 

 bug, including insecticides formerly used and others developed during 

 this investigation. Several preparations, including the resin wash 

 and a 2J per cent paraffin-oil emulsion, have given fairly effective 

 results: but two new sprays, cresolated distillate emulsion and soap- 

 powder emulsion, are recommended as best measuring up to orchard 

 requirements in mealybug control. The formulas for the preparation 

 of these sprays are given below. 



CRESOLATED DISTILLATE EMULSION. 



Distillate (28 Baume) gallons.. 2f 



Liquor cresolis compositus, U. S. P quarts If 



Liquid fish-oil soap quart 1 



Soap powder (sodium carbonate 40-60 per cent, caustic soda 



40-60 per cent) pounds.-- 3 



Water to make gallons.. 100 



Preparation. When the bottom of the spray tank is covered with water, 

 start the agitator and sift in the finely ground soap powder, which dissolves 

 while the tank is filling. Prepare the stock by first measuring the distillate, then 

 pour the liquor cresolis compositus into the distillate and stir. Pour into the 

 liquid soap twice as much of the foregoing mixture as of the soap and beat with 

 a paddle until of uniform consistency. Then add remainder of mixture and 

 stir thoroughly, after which the preparation is ready to be poured into the spray 

 tank. 



