34 FIRST REPORT OX ECONOMIC BIOLOGY. 



together, until the whole formed a buttery mass. This stock was 

 then reduced by adding- ^ gallons of soft water. 



" i8th January, 1907. The following branches were then dipped 

 into the wash tub and generally shaken in the fluid until all the parts 

 were thoroughly wetted : - 



Branch No. 7 on Spruce marked B, on which 23 hibernating Chermes 



were counted. 



Cl 5 >J 9 ^ ) > 



>? 9 " " " ^4 " 



10 marked F, . 83 



5) 1? M 37 " " 



n -I ** 11 11 11 O ** 



34 6 



Thus 6 branches on two different trees, bearing a total of 346 

 hibernating Chermes, were washed. On March 3ist, when the 

 Chermes on other branches of the same trees were seen to have 

 awakened, the washed branches were examined, and the Chermes 

 on them were apparently dead. Examined again on June i3th, not a 

 single gall was to be found on any of these branches. 



Two trees which have been regularly galled year after year, and 

 on which numbers of hibernating Chermes were found to be present, 

 were sprayed with the same wash on January i8th. With the exception 

 of about half a dozen galls on branches which the spray failed to 

 reach, both these trees are practically free of Chermes. 



A further trial of this wash was made on five badly infected 

 Spruces in the Cambridge Botanic Gardens, which Mr. Lynch, the 

 Curator, kindly had sprayed at my request. The buds were just 

 beginning to show signs of swelling, and there were numbers of 

 Chermes seated below the buds, which had just awakened and com- 

 menced to suck. 



On examining these trees on June i3th, I was unable to find a 

 single gall, though other trees close beside them were laden with galls. 

 No scorching of the foliage has occurred in any cast'. 



Wash No. 2. Another wash which also gave successful results 

 consisted of a solution of soft soap mixed in the proportion of i Ib. 

 soft soap to i gallon of soft water. 



A branch on which I counted some Ho to 90 Chermes was dipped 



