BULLETIN 256. 



ELM LEAF ROSETTE AND WOOLLY APHID OF THE 



APPLE.* 



Schisoneura lanigera (americana in part). 

 Edith M. Patch. 



White masses looking like patches of thick mold often occur 

 on apple trees, especially about pruning wounds or other scars 

 on the trunk and branches and upon water sprouts. Beneath 

 this substance are colonies of rusty colored or purplish brown 

 plantlice known as "woolly aphids" on account of the appear- 

 ance of white covering which is, however, really composed of 

 waxen filaments. 



The species is common in Maine on hawthorn, mountain ash, 

 and Baldwin and some other varieties of apple. 



It is one of the migratory aphids and passes part of its life 

 cycle upon the elm,** as is explained in the following treat- 

 ment. It should not however, be confounded with those woolly 

 aphids found upon alderf and maple,! as the woolly aphid of 

 the apple cannot live upon those trees. 



*Papers from the Maine Agricultural Experiment Station : Ento- 

 mology No. 91. The work upon which this bulletin is based was for 

 the most part completed in 1913 and published by this Station as Bulle- 

 tin 217, which is now out of print. As the interest in the insect con- 

 cerned continues and as the discovery of its annual migration from elm 

 to apple was first recorded by this Station, it seems desirable to print 

 this revised edition of Bulletin 217, containing such changes as bring 

 the subject down to date. Chas. D. Woods, Director. 



**There are other elm aphids belonging to this same genus which do 

 not migrate to apple. 



^Pemphigus tesscllata (acerifolii.) 



tPemphigus tessellata {acerifolii) and Pemphigus aceris. 



