82 NEW YORK STATE MUSEUM 



ring as it does, in oval, spiny bud galls on witch-hazel and upon 

 the leaves of birch. The season of 1909 was remarkable on ac- 

 count of the abundance of this species upon birch foliage, both 

 in the vicinity of Albany and Hudson and probably in other por- 

 tions of the State. The plant lice were so numerous as to cover 

 the foliage with honeydew, which was soon followed by the 

 development of the sooty fungus and the resultant blackening 

 of the leaves. A summary account of this plant louse, accom- 

 panied by illustrations, has been given by the writer.^ 



Witch-hazel cone gall ( H o r m a p h i s h a m a m e 1 i d i s 

 Fitch). Tlie conical, green or reddish galls of this plant louse 

 are more or less abundant upon witch-hazel leaves from year 

 to year and occasionally extremely numerous. This, like the 

 preceding form, migrates to the birches and also has a varied 

 and extremely interesting life cycle, v.diich latter has also been 

 summarized by the writer.- 



Hickory gall aphid (Phylloxera caryaecaulis 

 Fitch). This is one of the commonest of our Phylloxera galls 

 on hickory and presumably the most destructive, though some 

 other species are occasionally very abundant and undoubtedly 

 seriously affect the trees. The young galls of this species occur 

 in early June, at which time they vary from the size of a pea 

 tO' that of a small marble and range in color from pale greenish 

 to a bright pink. They are irregularly spheroid, being usually 

 prolonged at the union with the midrib or petiole and with a 

 more or less distinct, somewhat irregular, ventral orifice which 

 is completely closed. ]\Iany of the galls are so near each other 

 that they fuse. Each contains a central cavity with its stem 

 mother and numerous young* plant lice. Later the galls be- 

 come green or rosy and as they increase in size the plant lice 

 multiply to such an extent that during the latter part of the 

 period of growth, the inner surface of the gall may be literally 

 covered with numerous young, pale green plant lice. Finally, 

 the distorted tissues die, turn black and leave an ugly, shrunken 

 mass. This is only one of a number of species of Phylloxera 

 likely to occur upon hickory. Mr Pergande, who has made an 

 extended study^ of the species occurring upon hickory, divides 



'N. Y. State Mus. Mem. 8, 2:643. 

 -N. Y. State Mus. Mem. 8, 2:639. 



^ N. Amer. Phylloxerinae Affecting Hicoria (Carya) and Other Trees. 

 Davenport Acad. Sci. Proc. 1901. 8:185-273. 



