Galls caused by the larvae of Livia juncorum Latr 



on 



the leaves of Juncus articulatus Linn. 



PLATE lOS. 

 Synonymy of Insect. 



Habitat of the Jointed ROsh.— Grows in wet places 

 abundantly all over Britain, on the margins of ponds, 

 ditches, and marshes, also on the muddy or sandy parts 

 of railway banks. 



The Gall is formed by the leaves overlapping and en- 

 folding one another, being caused to do so by the larva 

 preventing the upward growth of the stem. 



Position. — At the base of the stem near the ground among 

 the surrounding grass. 



Manner of Growth. — Like a tassel ; two or three on one 

 stem. 



Colour. — Green ; sometimes the leaves are suffused with red. 



Average Dimensions of a Mature Specimen. 



Height, 80 mm. ; breadth, 30 mm. ; girth, 65 mm. 



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

 and October. 



The Growth is complete by the end of August. 



The Typical Condition of the gall is unilarval. 



The Larva pupates in the gall. The imago emerges 

 during ? 



These galls usually affect a very obscure situation. Low 

 down, very near the ground, and hidden by the surrounding 

 herbage, they escape observation until carefully searched for. 

 Very seldom do they appear level with or above the other 

 portions of the plant. When the clusters of leaves are held 

 with their tips pointing downwards, they resemble a tassel in 

 appearance. These clusters of leaves vary in number from 

 three to eight on a single stem, and some clusters consist of 

 from sixty to seventy leaves. 



The illustration is of specimens gathered at Guestling, near 

 Hastings, by the author. 



23S 



