22 



CIRCULAR 270, U.S. DEPARTMENT OF AGRICULTURE 



the fall .winged forms again develop and fly back to the apple trees, 

 where they produce a wingless generation of aphids which deposit 

 winter eggs on the twigs, in the axils of the buds, and in crevices in the 

 bark. These eggs are at first pale green but later become shiny black. 



CONTROL 



Control of the rosy apple aphid should be effected before the leaves 

 have been curled, as it is very difficult to accomplish afterward. As 

 aphids are sucking insects, contact insecticides rather than poisons 



must be used. A 

 spray containing 4 

 percent of oil de- 

 stroys a great many 

 of the young aphids 

 that are gathered on 

 the buds if it is ap- 

 plied just after the 

 eggs have hatched. 

 The dormant-season 

 application of lime- 

 sulphur solution is 

 relatively ineffective. 

 More thorough con- 

 trol will result from 

 using nicotine sul- 

 phate (40 percent 

 nicotine) in the pro- 

 portion of three 

 fourths of a pint to 

 100 gallons of water, 

 in combination with 

 the oil emulsion or 

 the lime-sulphur so- 

 lution. This appli- 

 cation must be com- 

 pleted before the tips 

 of the leaves have 

 begun to separate 

 (%. 25). 



GREEN APPLE APHID 



The green apple 

 aphid (Aphis pomi 

 DeG.) lives on apple 

 trees throughout the 

 year and feeds most- 

 ly on the succulent 

 terminal twigs (fig. 

 26), curling the leaves and stunting the growing shoots. It is thus 

 injurious chiefly to nursery stock and to young trees, although it 

 sometimes becomes sufficiently numerous on bearing trees to hinder 

 normal growth. It is occasionally found on pear trees. This aphid, 

 which came from Europe, is now found in the United States wherever 

 apples are grown. 



Figure 24.— Apples stunted by the rosy apple aphid. 



