8 



Bulletin 328 



the species Ijecomes eas}'. The aduk stem-mother of the oat 

 aphis is pale yellowish green, with a darker streak along the mid- 

 dle line of the back, while that of the green apple aphis is bright 

 green, and that of the rosy aphis has a slaty cast and is covered 

 with powder. 



Nature and Extent of Injury 



As soon as each species hatches from the egg it attacks such 

 of the young unfolding foliage as may be out. It works its 

 mouth parts through the rind of the plant and sucks out the 

 sap. As the liower Ijuds are exposed by the development of the 

 tree, thc\' in turn are attacked. 



Fit 



liiiur\' tn foliage 



The wounding of the tissue and the withdrawal of sap upsets 

 the rate of growth of the part attacked in such a fashion as to 

 cause curling of foliage and distortion of the fruit. 



The activitv of the oat aphis causes little curling of the foliage, 

 and as the second l)rood develops wings and leaves the tree by 

 the time the fruit has well set, the troul)le is soon past. To what 

 extent the feeding on the Inids and tiower clusters may so weaken 

 them as to ])revent setting, we do not know, 1)ut it is possible 

 that such an injury takes place. 



