Orchard Pests and their Control 365 



the tree may be very badly infested, and the cottony secretion 

 may be so heavy as to hang down and even fall from the bodies 

 of the lice. 



The lice are all wingless until about the first of September, 

 when an occasional winged louse may usually be found upon the 

 trees. They leave the trees where they develop and fly to others. 

 Each of these winged lice gives birth to about four or five males 

 and as many females. Before winter comes on, each female de- 

 posits a single egg and dies. No one seems to have followed this 

 part of the life history of the woolly aphis in the orchard. It is 

 supposed that these eggs hatch the following spring and start new 

 colonies. 



The woolly aphis lives on the roots in large numbers the year 

 round, the only difference in the winter being that the lice re- 

 produce very slowly, and so do not increase much in numbers. 

 The cold weather seems never to be sufficient to kill them even 

 in our coldest climates where the apple is grown. 



Prevention is nearly always better than cure. Great care 

 should be taken, therefore, when setting out a new orchard, to 

 prevent the introduction of this louse. Orchards are usually in- 

 fested by the lice that are on the roots of the nursery trees when 

 they are set out. All nursery stock should be thoroughly disin- 

 fected either by fumigation w r ith hydrocyanic acid gas, or by 

 very thorough spraying of the trees, both roots and branches, 

 before they are set, with one of the remedies mentioned below 

 for spraying tops. 



One method of preventing injuries from this louse is to have 

 all apple trees on Northern Spy roots, as Northern Spy seems 

 never to be seriously attacked. 



If nursery stock is received with roots "puddled" (covered 

 with mud), the purchaser should insist upon this mud being 

 thoroughly washed off, and the roots treated for woolly aphis, as 

 this is one of the methods that the nursery man has of covering 

 up woolly aphis. 



To prevent the spread of the woolly aphis from tree to tree 

 and orchard to orchard, the lice should be well cleaned out of the 

 orchard before the first week of September, as it is about this 



