Galls caused by the larvae of Cecidomyia violae F. 



the leaves of Yiola canina Linn. 

 PLATE 92. 



Synonymy of Insect. 



Cecidomyia viola Theobald. 



Habitat of the Dog-violet. — Freely distributed through- 

 out the whole of Britain in woods, thickets, by streams, on 

 hedge-banks, and other open, dry, or sandy situations. 



The Gall is formed by the basal edges of the leaf rolling 

 upwards and towards the mid-rib until they nearly meet. 

 Always at the basal portion of the leaf ; the apex is never 

 rolled. 



Manner of Growth. — Three or four leaves in one cluster 

 may be affected. 



Colour. — Dark green, sometimes streaked with purple. 



Average Dimensions of a Mature Specimen. 



Length, 20 mm. ; breadth, 8 mm. ; girth, 20 mm. 



May be sought during the months of July to December. 

 The Growth is complete by the end of October. 

 The Typical Condition of the gall is multilarval. 

 The Larv^ pupate in the gall. The imagines emerge 

 during the spring. 



Although the months during which these galls may be found 

 are scheduled as July to December, they may nevertheless be 

 obtained on some sheltered roadsides until March or April. 

 For the purpose of rearing the inhabitants, it is best to get 

 them as late in the spring as possible. If a plant be put in 

 a flower-pot in September or October and kept at home, the 

 same results may be obtained with little trouble. No leaf is too 

 small but that it is liable to attack. A cluster was once found 

 consisting of twenty-two leaves, eighteen of which were galled. 



The illustration is of specimens gathered at Hastings by the 

 author. 



216 



