INSECTS INJURIOUS TO THE APPLE AND PEAR 519 



in some instances. The aphids may be destroyed on the foliage 

 by spraying with 7 per cent kerosene emulsion, miscible oils 

 diluted 30 to 40 times, whale-oil soap, 1 pound to 6 gallons, or 

 tobacco extracts, u black leaf -40 " being used 1 part in 700 of water. 

 Whatever insecticide is used must be applied in a strong spray 

 so as to wet thoroughly and penetrate the waxy covering of the 

 aphids. A winter spray of lime-sulphur wash destroys the hiber- 

 nating aphids on the trunk, 

 and doubtless kerosene 

 emulsion or miscible oils 

 applied in early spring, 

 as for the San Jose scalei 

 would be as effective, 

 though the lime-sulphur 

 would probably also de- 

 stroy some of the eggs. 

 The trunks of trees known . 9 



to be infested may be FIG. 448. Sexual female and male of the 

 banded with tanglefoot 7 oll y apple-aphis greatly enlarged. 



... (After Alwood.) 



or similar sticky mater- 

 ials as described for canker worms (p. 502) to prevent the 

 aphids from migrating from the roots to the top. Where 

 the aphids are abundant on the roots, the earth should be 

 removed for 6 or 8 inches deep over the affected roots and 

 lime-sulphur solution, diluted about one to eight, applied in 

 quantities sufficient to wet the soil thoroughly about the roots. 

 Other solutions tried for soil treatment have given less success 

 than this. 



Some success has been reported by Leach from the use of 

 carbon disulphide in water solution, one ounce to four gallons, 

 applied about the roots with a power sprayer. Sodium cyanide 

 solution, applied in the same way also gave fairly good results. 

 With any of these methods there is the disadvantage that they 

 require large quantities of water to be transported to the orchard 

 and all are somewhat expensive. 



Liberal fertilization, to enable the tree to do well in spite 

 of the presence of the aphids is probably more practical for most 

 growing conditions. 



