Galls caused by the larvae of Rhodites nervosus Cam. 



on 



the leaves of Rosa canina Linn. 



PLATE lis. 

 Synonymy of Insect. 



Rhodilus nervosus Curtis, Marshall. 



Rlwdites rosarufu Giraud, Schen., Tasch., Galleii, Fitch, 

 Cameron. 



Habitat of the Dog-rose.— This is the commonest rose in 

 Britain, and grows rapidly and luxuriantly in hedges, 

 thickets, and various dry places in all parts of the country. 



The Gall is formed by an enormous accumulation of sap, 

 drawn from the leaf, which passes through the slender 

 pedicle with very great rapidity. 



Position. — On the under surface of the leaf 



Manner of Growth. — Glabrous ; more or less globular ; with 

 stout sharp-pointed spines radiating from the surface. 



Colour. — Pale green, spotted or suffused with red, turning to 

 dull brown when mature. 



Average Dimensions of a Mature Specimen. 

 Girth, 1 8 mm. 



May be sought during the months of July to October. 



The Growth is complete by the end of August. 



The Typical Condition of the gall is unilocular and unilarval. 



The Larva pupates in the gall. The imago emerges during 

 the following spring. 



Inquiline. — Periclistus canina Cam. 



Parasites. — Torymus macropterus, Pteromalus emviens Foer., 

 P. inflexus Foer., Tetrastichiis obtusaius Gir. 



The gall is also figured by Peter Cameron, " British Phyto- 

 phagous Hymenoptcra" (Ray Society), vol. iv., plate ii. 

 257 17 



