Galls caused by the larvae of Cecidomyia bursaria 

 Bremi. 



the leaves of Glechoma hederacea Linn. 



PLATE 78. 



Synonymy of Insect. 



Cecidomyia bursaria Theobald. 

 Habitat of the Ground-ivy. — This plant is very abundant 



in Britain, growing in waste places and on banks ; but 



its favourite situations are the edges of woods and under 



hedges. 

 The Gall is formed by the vegetable cells arising from the 



upper surface of the leaf and forming a tubular structure 



covered with hairlets. 

 Position. — It is situated on any part of the leaf except the 



mid-rib. 

 Manner of Growth. —Gregarious, as many as eleven on 



one leaf. 

 Colour. — Pale green at first, becoming darker at base and 



reddish at apex. 

 Average Dimensions of a Mature Specimen. 



Height, 5 mm. ; girth, 6 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. 

 The Larva pupates in the gall. The imago emerges during 



the following spring. 



The development of these galls may be easily watched in 

 one's study or conservatory. If a root of the plant with its 

 runners bearing affected leaves is potted with its natural soil, it 

 will continue to grow and the gall-structures develop ; or a leaf 

 may be kept alive in water, but the result is not so certain. 



The gall is also figured by F. V. Theobald, " British Flies," 

 p. 71 ; Bremi, plate 1, fig. 20. 



