EELWORM GALLS 



109 



Tylenchus devastatrix attacks various Clovers, causing arrest 

 of development. The internodes are shortened and thick- 

 ened, and the leaves deformed, with involute margins. It 

 also attacks the Buckwheat, causing thickening of the 

 stems, shortening of the internodes, and enlargement of the 

 leaves. It causes bulbous swellings at the base of the stem 

 of the Sweet Vernal Grass, Shepherd's Purse, and other 

 wild plants. According to Connold, it is responsible for the 

 deformed shoots and bulbous swellings on the lower part of 



26 28 



Fig. 26 — Stem Eelworms (Tylenchus devastatrix). (Greatly magnified.) 

 Fig. 27 — Anterior Portion of a Female, showing the Mouth- 

 spear. (440/1.) 

 Fig. 28— Embryo in Egg. (Greatly magnified.) 



From figures by Dr. J. Ritzema Bos. Reproduced from Miss Eleanor 

 Ormerod's "Manual of Injurious Insects," by permission of 

 Messrs. West, Newman and Co. 



the stem of the Wild Teasel. Houard attributes the galls 

 on the Teasel to a Tylenchus, but leaves the species in doubt. 

 I think I have seen it alluded to as Tylenchus dipsaci, but 

 cannot find the reference. In T. devastatrix there is but one 

 generation annually. Each female produces from 600 to 

 I, OOP ova. Miss Ormerod observes that "the exceeding 



