208 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



of barium with sulphur. The dry barium-sulphur is the material 

 already described, the chief ingredient of which is barium tetrasulphide. 



It will be noted that the barium product killed the scale quite as 

 effectually as the lime-sulphur solution, and that there was practically 

 no difference in the effect of the dry form and the solutions. Calcium 

 thiosulphate had no material effect on the scale, while calcium sulphide 

 apparently did. However, these two materials were used on only 

 one tree each which is not sufficient for conclusive results. The barium 

 products were used on about 200 trees. 



Another experiment comparing the dry barium-sulphur product with 

 lime-sulphur solution in the control of the San Jose scale was conducted 

 in a three-year-old orchard near Hancock, Md. This orchard is com- 

 posed of peaches and apples interplanted, and the plots were so ar- 

 ranged that each contained at least one apple and one peach tree badly 

 infested with the San Jose scale. About 200 trees were sprayed with 

 the dry barium product and a like number with lime-sulphur solution. 

 The application was made on March 25 and 26, 1914, and the trees 

 were examined several times during the spring and summer. The 

 results of examinations made on May 30 and July 4 are shown in 

 Table IT. 



Table IL San Jose ScAy.E Experiment, Hancock, Md., March 25-26, 1914. 



Plot 



Materials 



Lbs. to 50 gals. 

 Water 



Per cent Scale 

 Dead 

 5-30-14 



Young Alive 

 7-4-14 



1 



Dry barium-sulphur (a) 



16 



99i 



None 



2 



Drv barium-sulphur . 



24 



100 





3 



Dry barium-sulphur 



32 



100 





41 





59 



99i 





5 





16 



99i 





6 



Dry barium-sulphur 



^4 



99i 





7 



Dry barium-sulphur 



32 



99i 





8 



Dry barium-sulphur (c) 



16 



100 





9 



Dry barium-sulphur 



24 



99 





10 



Dry barium-sulphur 



32 



100 





11 



Dry barium-sulphur 



10 



99^ 





12 



Check 



llnsprayed 



50 



Many 



(a) represents the dry BaS4H20 with all the impurities, (6) the same material with most of the impurities removed, 

 and (c) the same as (6) but prepared in a somewhat different manner. 



1 Plot 4 was sprayed with lime-sulphur solution (320-33" Beaum6) diluted at the rate of 5| gallons (59 lbs.) to 50 gallons 

 of water. 



As shown by the figures in Table II there was practically no differ- 

 ence in the insecticidal effect of the barium-sulphur crystals and lime- 

 sulphur solution. An examination on May 30 showed from 99 per 

 cent to 100 per cent of the scale dead on all the sprayed plots and 50 

 per cent on the unsprayed plot. On July 4, crawling and newly settled 



