2()2 MAIM-. AC.KICIT/I TK.xL EXl'KUl M EXT STATIOX. I906. 



The ants which attend colonies of plant lice so industriously 

 do not injure them in any way, but are there merely to gather 

 the honey dew. 



Remedies. Where shade elms are thus affected year after 

 year, watch may be kept for the first signs of deformed leaves 

 early in the season. If these are removed and burned the 

 later numerous generations will not have a chance to develop. 

 As the stem-mothers usually choose a terminal twig on which 

 to start a colony, it is not a difficult matter to keep a young tree 

 comparatively free from leaf-curl. Before the leaves become 

 much curled, kerosene emulsion is an efficient remedy for 

 frequent sprayings early in the season. 



As a rule the trouble involved makes either of these meas- 

 ures impracticable when applied to very large trees. There 

 is then nothing to be done except to endure the leaf-curl and 

 leave the plant lice to their natural enemies, who find in the 

 task of extermination both enjoyment and a means of suste- 

 nance. 



The species of plant louse found in elm leaf-curl does not 

 attack other trees and thus need not be feared as a general pest. 



^Nlany other species of plant lice, however, have similar 

 habits, as the ordinary plum aphis, or the snowball aphis, both 

 common in this State. Where any valuable trees and shrubs 

 are attacked year after year by leaf-curling plant lice, the clip- 

 ping and destruction of the first deformed leaves and early 

 spraying with kerosene emulsion are usually the only available 

 remedies and are often perfectly practical. 



