318 Insect Pests. 



THE WALNUT LEAF-GALL MITE. 



(Eriophyes triseriatus v. crinea. Nalepa.) 



This mite causes bladder-like swellings on walnut leaves, the 

 under surface being hollow and lined by a white, velvety substance. 

 The acari are very minute and very transparent. 



Although disfiguring to the foliage, I have never seen any real 

 damage caused by it. This form is most common on the walnut, but 

 the type species Eriophyes triseriatus now and then occurs. The galls 

 formed by them are quite different, being in the form of brownish- 

 red galls about the size of a pin's head, slightly projecting on the 

 upper and under sides of the leaves. The mites appear to enter 

 through the stomata, as in the pear-leaf species (p. 353), and may 

 be found in the soft cellular tissue in great numbers. Some mites 

 are brownish in appearance and only ^ mm. in length. Formerly 

 called ' Ccphaloneon bifrons, Bremi. 



REFERENCES. 



(1) Murray, A. ' Economic Entomology. Aptera,' p. 370 (1887). 



(2) Houard, C. Les Zoocecidies cles Plantes d'Europe,' p. Ill (1908). 



(3) Nalepa, A. ' Systematik der Gallmilben,' p. 51. 



