10 



INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



Fig. 10. — Leaves of the California black walnut showing gall-like 

 blisters produced by the walnut blister-mite, Eriophyes tristriatus 

 Nalepa. Natural size. (Original) 



buds are beginning to open. Late applications after the blisters are 

 formed would be useless, as the mites are hidden and protected by the 

 felt-like pads. 



ERINOSE OF THE VINE 



Eriophyes riti.s Landois (Family Eriophyidse) 



(Fig. 11) 



Description. — The mites are silvery white or light yellow, somewhat 

 cone-shaped with head end largest and tapering to a point at the tail. 

 The body is encircled with many fine lines and the two pairs of legs 

 are close to the head. They are exceedingly small and can be seen 

 only with keen eyes or with the aid of a magnifying glass. The work 

 is very characteristic, consisting of thickened felt-like pads made on 

 the undersides of the leaves, causing a swelling on the upper and a de- 

 pression on the lower surfaces of the leaves. Beneath the felt-like pads 

 are first very light green, but they eventually become dark brown. 



Life History. — The place of hibernation of the mites has been prob- 

 lematic to some, but from the nature of early treatments, which con- 

 sisted in drenching the trunks of the vines during the winter, they 

 must conceal themselves in cracks or under the bark or under the 



