Galls caused by the queen, larvae, and nymphs of 

 Schizoneura ulmi Linn. 



on 



the leaves of Ulmus montana Sm. 



PLATE 107. 

 Synonymy of Insect. 



Aphis foliomm De Geer. 



Schizoneura ulmi Kalt., Kotch., Pass., Riley, Thomas, 

 Kerner, Buckton. 



Habitat of the Scotch, or Wych, Elm.— In parks, plan- 

 tations, avenues, and gardens generally throughout Britain. 



The Gall is formed by the leaf being rolled, blistered, and 

 thickened by the aphides, which live within the roll and 

 draw nourishment therefrom. 



Position.— On either half of the leaf 



Manner of Growth.— Very rarely more than one roll on 



a leaf 

 Colour. — Green, yellowish green, pale ashy grey. 



Average Dimensions of a Mature Specimen. 



Length, 50 mm. ; greatest diameter of roll, 13 mm. 

 May be sought during the months of June to October. 

 The Growth is complete by the end of August. 



The Typical Condition of the gall is multilarval and 

 multinymphal. 



ECDYSIS takes place within the gall. The imagines emerge 

 during July and August. 



Considering how great is the deformity of the galled half of 

 the leaf, it is remarkable that the unaffected half should be so 

 vigorous in its development, which is almost normal. The 

 affected leaves occur on the lowest branches as well as at the 

 summit of the tree. 



The gall is also figured by Buckton, " British Aphides," 

 vol. iii., plate 108 ; A. Kerner, " Nat. Hist, of Plants," vol. ii., 

 P- 533- 



245 



