Galls caused by the larvae of Hedya aceriana Dup. 



on 



the twigs of Populus alba Linn., var. canescens 



PLATE 36. 

 Synonymy of Insect. 



Spilonota aceriana Mann. 



Habitat of the White Poplar. — In Britain this tree is 

 .seldom found in a wild state. It prefers the edges of 

 streams, ponds, and other damp situations, often forming 

 a striking feature in large gardens and private grounds. 



The Gall is formed by the swelling of the young shoot as 

 a result of irritation due to the presence of the larva. 



Position.— At the end of the twig. 



Manner of Growth.— Singly ; slightly pubescent. 



Colour.— Silvery white. 



Average Dimensions of a Mature Specimen. 

 Length, 18 mm. ; girth, 24 mm. 



May be sought during the months of June, July, and August. 



The Growth is complete by the end of July. 



The Typical Condition of the gall is unilocular and uni- 

 larval. 



The Larva pupates in the gall. The imago emerges during 

 August. 



The larva eats its way into the young shoot, causing it to 

 bulge considerably. In course of time cracks appear on the 

 surface, disclcsing dark brown decaying tissue within. After 

 the escape of the imago, one crack widens until the interior of 

 the cavity is laid bare. The larva ejects its fras through an 

 opening at the top of the larval chamber, and instead of falling 

 away it is retained, and a bag-like pendant mass is formed on 

 the outside. 



The illustration is of specimens gathered at Hastings by the 

 author. 



