ORCHARD INSECTS 297 



hatches in the spring and the female attacks the opening leaf, 

 on which she gives birth to scores of young and soon causes 

 the leaf to twist up or " rosette." These young become 

 winged and migrate to the apple, where they give birth to a 

 wingless generation which lives on the twigs, and which, in 

 turn, gives rise to a fifth generation which crawls down to the 

 roots, and seems to do the most damage of any during mid- 

 summer. 



The aphides may be destroyed on the foliage by spraying 

 with 7 per cent kerosene emulsion, miscible oils diluted 30 

 or 40 times, or tobacco extracts, "Black-leaf 40" being used, 

 one part in 70 of water. A strong spray must be used so as 

 to penetrate the waxy covering and wet the aphides. A 

 winter spray of miscible oil, kerosene emulsion, or lime- 

 sulphur will destroy the hibernating aphides on the trunk 

 if applied so as to go beneath loose bark. Where injury is 

 being done to the roots, the earth above them should be 

 removed for 6 or 8 inches deep and enough 10 per cent kero- 

 sene emulsion or dilute tobacco extract should be applied to 

 wet the soil thoroughly. Dilute miscible oil might be used 

 in the same way and some success has been secured with 

 lime-sulphur mixture. Where tobacco stems or dust may 

 be secured cheaply, they should be applied in the same way. 

 The surface earth should then be replaced. Nurserymen 

 commonly use tobacco dust in the trenches along the rows 

 and also destroy the aphides on the foliage by spraying. 

 Means of controlling this pest have never been satisfactorily 

 determined, but as its migration to and from the elm tree 

 has been only recently discovered, it is believed that greater 

 advance in methods of control may soon be expected. 



157. The Peach-tree Borer.* (42). Possibly as many 

 peach trees are killed by borers as by any other pest. Their 

 * Sanninoidea exitiosa Say. Family Sesiidce, see page 79, 



