Galls caused by the larvae of Eurytoma hyalipennis 



on 



the haulms of Aramophila arundinacea Host. 



PLATE 41. 

 Synonymy of Insect. 



Habitat of the Sea Matweed.— This interesting grass is 

 frequent on the British coasts, more especially in Norfolk, 

 Northumberland, and the coast of Sussex to the eastward. 



The Gall is formed by the irritation caused by the larva, 

 which feeds upon the medullary tissue and prevents further 

 upward growth. 



Position. — At the top of the haulm ; sometimes obscure 

 amongst the other grass. 



Manner of Growth. — Solitary. 



Colour. — At first the leaves are deep pink, which, as growth 

 proceeds, become lighter, ultimately assuming a straw- 

 colour. 



Average Dimensions of a Mature Specimen. 

 Height, 45 mm.; girth, 21 mm. 



May be sought during any month in the year. 



The Growth is complete by the end of October. 



The Typical Condition of the gall is unilocular and uni- 

 larval. 



The Larva pupates in the gall. The imago emerges during 

 June. 



The plant upon which these galls are found is known as 

 the common sea-grass, the sea-reed, the marum, the matweed, 

 and esparto grass. It grows by the seashore beyond high- 

 water mark, and by the abundance of its creeping, fibrous, and 

 entangled roots, assists in producing the elevated ridges known 

 as .cand dunes, by retaining the grains of sand which otherwise 

 would be carried by the wind farther inland. 



