128 



ORDER HEMIPTERA 



where in tlie spring of the following season they produce 

 rosette galls, later migrating back to the apple. The rosette 

 gall has been separated from the leaf curl gall produced by 

 Schizoneura americana, a species that is a frequent pest on 

 elm trees. 



Fig. So. — \\'<)olly aphis on apple twigs. (Photo from Ohio Exp. Sta.) 



Remedies for the root form are difficult, but for orchard 

 trees after removal of the earth, sprinkle tobacco dust on 

 the roots and replace the soil. The use of 10 per cent, 

 kerosene emulsion can also be recommended. Above ground 



