138 



KEPOET 108^ U. S. DEPARTMENT OF AGRICULTURE. 



Another injurious species in this country is the plum-twig gall mite, Eriophyes 

 phloeocoptes Nalepa (also known as Ceddoptes pruni Amerling). It is an European 

 species that has been imported into this country in recent years. The mites form 



small subspherical galls at the base of the buds. 

 A cluster may surround the twig. The mites 

 hibernate within the galls, lea\4ng them in the 

 spring to form new ones. The galls are at 

 first plump and smooth, but later become 

 dry and wrinkled and sometimes crack. Prun- 

 ing and burning the infested twigs in winter 

 will keep the mites in check. An application 

 of sulphur in the spring when the mites are 

 active will doubtless destroy many of them. 



The black-currant gall mite, Eriophyes ribis 

 Nalepa, is very injurious to the currant in Eng- 

 land. They penetrate the buds, causing them 

 to swell, and badly infested buds die before 

 opening. The mites breed throughout the year. 

 They migrate in the spring when the buds are 

 opening and may be destroyed at this time by 

 It has been observed that 



. — Round galls of an Eriophyes. 

 (Author's illustration.) 



/ 



^^:^^ 



a wash of soft soap and sulphur 



this species can stand upright and even jump into the air and be 



carried some distance by the wind. 



In California the Eriophyes vitis Landois (fig. 289) often seriously 

 injures the leaves of the grape. The mites produce an erineum 

 on the under surface of the leaf that causes swellings on the upper 

 surface. The mites pass the winter in the buds or under the 

 bark of the vine. Applications of sulphur will destroy this as 

 well as other species of Eriophyes. Erineimis and galls occur 

 on a great number of our native trees and plants. Some of the 

 more common of these are mentioned below, but many of our 

 forms are yet to be described, and in most cases the mites have 

 not been studied in a careful manner. Recently Hodgkiss has 

 described the numerous species on maples. 



A small rounded gall on ash leaves is made by E./raxini Garman. 

 A deformation of the terminal buds of the white ash is caused by 

 E. fraxiniflora Felt. On maples there are several galls. A simple 

 erineum (yellowish to brownish in color) on the under surface of the 

 leaves is tenanted by E. ryderi Banks. A small, irregularly rounded 

 gall, often extremely numerous, is produced by E. quadripedes 

 Shimer, and is at first green, then purplish, and finally black. Elon- 

 gate pouch galls, rarely numerous, are made by E. acericola Garman. 

 In the red erineum on the upper side of the leaves of sugar maple 

 Hodgkiss has found three species of Eriophyes, two species of 

 Phyllocoptes, and one Oxypleurites. In the pink erineum on the 

 under surface of leaves of the red maple he found two species of 

 Eriophyes and one Phyllocoptes. On oaks it can also be noted 

 that erineums are more apt than galls to be tenanted by several 

 species of mites. A wartlike gall on leaves of Negundo, or 

 black maple, is produced by Eriophyes ncgnndi Hodgkiss. In 

 blisters on the bark of red maple Hodgkiss found a species of Anthocoptes. 



On the black walnut and butternut there is a very dense brown erineum surround- 

 ing the leaf stalks or main veins of the leaf, caused by E. caidis Cook, while an erineum 

 (usually very large) on the surface of the leaf is produced by E. criiica Nalepa. This 



Fig. 2^9.— Eriophyes 

 vitis. (Author's 

 Illustration.) 



