EPIDEMIC OF SILVER MAPLE LEAF-MITE. 



PHYLLOCOPTES (ERIOPHYES) QUADRIPES SHIMEE. 



By Alfred C. Burrill. 



The silver maple (Acer saccharinum) shade trees along the 

 streets of Whitefish Bay, Wis., a suburb north of Milwaukee, 

 were plagued this summer with an unusual abundance of the 

 Bladder Maple Gall. It is made by the invisible mite known in 

 literature as Briophyes (Phytoptas) quadripes Shimer, the mate- 

 rial having been identified for me through the kindness of 

 Wm. Beutenmiiller, Entomologist of the American Museum, New 



York City. 



In answer to the queries of residents along Day Avenue, 

 Whitefish Bay, I looked up the literature for remedies, relying on 

 Dr. E. P. Felt's "Insects Affecting Park and Woodland Trees," 

 which gives a very good description, Vol. 2, pp. 630-1. The col- 

 ored plate I. fig. 11, however, shows galls of a slightly different 

 form from those common at the Bay. As this account gave no 

 literature or remedial measures, I wrote Dr. Felt, who most kindly 

 furnished me with eleven references, to six of which I had access, 

 and these mostly very meagre accounts. 



GEEAT DISFIGUEEMENT BUT SLIGHT DAMAGE. 



Prof. H. Garman also kindly wrote me, "The mite is common 

 in the Mississippi Valley, and is sometimes very abundant on the 

 leaves of the soft maple, though I have never known it to occa- 

 sion very serious harm to the trees. Like other insects, I suppose 

 it may do some local mischief, though commonly not to be feared." 

 Dr. Felt's 1906 account states, p. 630: "This trouble is some- 

 times exceedingly prevalent in the vicinity of Albany, the galls 

 being so numerous on certain trees as to disfigure a very consider- 

 able proportion of the foliage." 



The descriptions of the galls by the various writers show a 

 variation from discoidal to spherical, with slightly constricted neck 

 approaching to top-shaped forms, beginning as a green swelling 

 on the dorsal surface of the leaf, and changing through varying 

 shades of pink and purple but chiefly red or green, to black or 



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