26 LI^E HISTORY OF THE ALDER BLIGHT APHIS. 



colonies as a measure to prevent the maturing of the return migrants. 

 Still later in the season it is advisable to spray all of the remaining 

 '.tumps of the shrubs, as well as the accumulated dry leaves and other 

 debris surrounding them, with a dilute solution of kerosene emulsion, 

 in order to destroy the hibernating larvae. If these shrubs are kept 

 down for a few years there will be no chance for the migrants from 

 maples to deposit their larvae and consequently no return migrants 

 to fly back to the trunks of maple trees. 



