REPORT OF THE SOCIETY 33 



they soon kill them or prevent further growth. They do not produce any 

 serious curling of the leaves, and when serious curling is seen it is pretty 

 certain to be caused by the rosy aphis. Neither do they do so much damage 

 to the setting fruit though here the amount of injury depends altogether 

 on the extent of infestation. Their work on the fruit is identical to that pro- 

 duced by the rosy aphis. However, as this species remains on the apple 

 throughout the season its injurious efifects are not confined to the early 

 summer months but it may by its continued work retard growth, prevent 

 the full development of the fruit, and injuriously affect the setting of fruit- 

 buds for the next year's crop. 



In the fall, early in October or late in September, appear small wing- 

 less females and true wingless males. This is the egg-producing generation. 

 All summer long generation followed generation without the intervention 

 of males, but now in order to tide the species over the winter eggs must be 

 developed. Each female, if it succeeds in mating with a male, lays from 

 two to six fertile eggs. As the males are generally very few in number 

 thousands of infertile eggs are laid and these shrivel up without ever hatch- 

 ing. 



Before proceeding to a discussion of control measures, I wish to point 

 out the conditions which give us such severe aphis infestations in June, 

 just at the time when the apple is setting its fruit and requires all the 

 nourishment it can secure. 



Towards the end of June, at Ithaca, N.Y., the stem mothers both of 

 the rosy and green aphis have ceased reproducing. The second generations 

 of both species have probably just reached their maximum productive 

 capacity about the middle of the month, while the third generations have 

 well begun and will reach their maximum during the last week of June, 

 and the fourth generation of the green aphis (Aphis pomi) has also begun 

 reproducing. Such rapid reproduction by these two species during June 

 soon produces the severe infestations which are so common during the 

 latter part of June and early July. When these species are abundant I 

 have seen trees so heavily infested in the early days of July that not a pin 

 could be stuck into the tree anywhere without piercing several plant lice. 

 In such infestation the loss amounted to several thousand dollars worth 

 of fruit in a comparatively small orchard. 



