Galls caused by the larvae of Hormomyia Fagi Hartig. 



on 



the leaves of Fagus sylvatica Linn. 

 PLATE 96. 



Synonymy of Insect. 



Cecido7nyia fagi Mosley. 



Hormomyia Fagi Theobald. 

 Habitat of the Common Beech.— A large and tall tree of 



majestic and noble proportions. Grows in woods and 



forests in every part of England, where it is extensively 



planted. 

 The Gall LS formed by the deposition of an ovum in the 



upper surface of the leaf causing a glabrous cone-shaped 



structure. 

 Position.— On any part of the leaf, but principally near the 



mid-rib. 

 Manner of Growth. — Gregarious ; glabrous. 

 Colour. — Green, then yellowish, and bright red at apex. 

 Average Dimensions of a Mature Specimen. 



Height, 4 mm. ; girth, 4 mm. 

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



September. 

 The Growth is complete by the end of August. 

 The Typical Condition of the gall is unilocular and uni- 



larval. 

 The Larva pupates in the gall. The imago emerges during 



the spring. 



As far as the author's observations have extended, these 

 galls are never so numerous as those of H. piligera. They are, 

 however, scattered over the leaf in the same manner and mostly 

 near the mid-rib. The under surface of a leaf in the centre of 

 the left-hand half of the illustration shows a number of slightly 

 raised pimples indicating the presence of galls on the upper 

 surface. At the approach of winter the galls fall off, the larvae 

 remaining within. They pupate in the following spring, and 

 after a few days the imagines begin to emerge. 



The illustration is of specimens gathered at Hastings by the 

 author. 



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