Galls caused by the larvae of Ceuthorhynchus 

 sulcicollis Gyll. 



on 



the roots of Brassica sinapis Visiani. 



PLATE 11. 

 Synonymy of Insect. 



Ceuthorhynclius pleurostigvia Marsh. 

 „ sulcicollis Payk. 



Habitat of the Charlock.— A most abundant weed in 



every part of Britain, affecting railway banks, edges of 



fields, road sides, and waste ground generally. 

 The Gall is formed by the irritation to the tissues caused 



by the feeding of the larva. 

 Position. — On the subterranean portion of the stem, and the 



roots. 

 Manner of Growth. — Singly and gregarious ; glabrous ; 



globular (usually). 

 Colour. — Same as the root itself. 



Average Dimensions of a Mature Specimen (globular 

 form). 



Girth, 48 mm. 

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



and September. 

 The Growth is complete by the end of July. 

 The Typical Condition of the gall is unilocular and unilarval. 

 The Larva pupates in the ground. The imago emerges 



during the spring. 



On the common charlock the harm which the larvae do to 

 tl-.e growth of the plant is not worth notice. But with the 

 cultivated Brassiae it is quite different. Among these the 

 larvas cause considerable destruction by diverting the sap for 

 their own nourishment, and, when they leave the larval chamber 

 to pupate, they make a hole through which wet and fungus 

 penetrate and cause premature decay. 



The gall is also figured by Miss Ormerod, "Injurious Insects," 

 P- 35- 



The illustration is of specimens gathered at Hastings by the 

 author. 



