Insects and Other Enemies 343 



four gallons of kerosene. Churn these well together 

 by pouring or pumping for fifteen or twenty minutes. 

 When ready to use, add sixty to one hundred gallons 

 of water. This recipe can be halved or quartered, if 

 smaller quantities of the emulsion are needed. There 

 are several other formulas for making the emulsion, 

 but all give about the same results. Two or three ap- 

 plications of the kerosene emulsion will probably be 

 required to clear out the aphis. Care must be taken 

 not to make it too strong, for sometimes it damages 

 the young shoots more than do the insects. 



The Plum Lecanium scale. — This plum scale (Le- 

 canium prunastri) occasionally gives trouble. Slinger- 



THE PLUM LECANIUM SCALE 



land relates that in 1894 in one orchard of over 2000 

 trees in New York, "one-fourth of the immense crop 

 was not worth picking and most of the remainder was 

 badly damaged." These scales may readily be seen 

 at any time on the twigs and branches. Their general 

 appearance is plainly indicated in the cut. This 

 pest can be combated to best advantage during the 

 winter, when it should be sprayed two or three times 

 with strong kerosene emulsion. 



The San Jose scale (Aspidotus perniciosus). — This 

 scale insect attacks plum trees, in common with nearly 

 all other fruits. So much has been said and sung about 

 this special pest of late, however, that no general ac- 



