Galls caused by the larvae of Retinia resinella Linn. 



on 



twigs of Pinus sylvestris Linn. 



PLATE 37. 

 Synonymy of Insect. 



Parasite. — Glypta resinana. 



Habitat of the Scotch, Norway, or Riga Pine-tree. — 

 To be found all over Britain. It is indigenous in the 

 Scotch highlands. 



The Gall is formed by the larva feeding upon the young 

 shoot and causing an accumulation of resinous sap around it. 



Position. — At the end of the twig. 



Manner of Growth.— Singly ; glabrous ; resinous ; somewhat 

 ovid in outline. 



Colour — Dull grey with darker patches. 



Average Dimensions of a Mature Specimen. 



Length, 25 mm.; breadth, 18 mm.; girth, 40 mm. 



May be sought during the whole of the year. 



The Growth is complete by the end of the autumn. 



The Typical Condition of the gall is unilarval. 



The Larva pupates in the gall. The imago emerges during 

 March. 



These galls appear to be almost entirely confined to Scotland 

 and the northern counties of England. The ovum is laid 

 among the buds at the extremity of a young shoot, and as soon 

 as the larva hatches it feeds upon and within the stem, causing 

 exudation of sap, which encloses the larva and increases in size 

 until pupation takes place. 



The gall is also figured in "The Royal Natural History," 

 sect, xi., p. 120. 



The illustration is of specimens supplied by Mr. F. W. Terry, 

 of South Kensington Natural History Museum. 



