REPORT OF THE STATE ENTOMOLOGIST I909 83 



the galls into three groups. The thin, paperlike or more or less 

 transparent ones occurring upon leaves, the thicker, fleshy, 

 variform galls alwavs opening beneath and on leaves, those 

 forming elongate folds along the veins, and finally, a fourth 

 class represented by the species discussed above, producing galls 

 on the twigs or leaf petioles. Phylloxera galls on hickor}^ leaves 

 are frequently very numerous and are produced by a number of 

 species, though the leaf inhabiting species are rarely abundant 

 enough to cause material injury. The Phylloxera galls usually 

 have a distinct orifice and may be distinguished from similarly 

 appearing Cecidomyiid galls by the minute plant lice within. 



Red elm leaf gall (Pemphigus ulmifusus Walsh) . 

 The large, solitary, spindle-shaped galls about i inch long, pro- 

 duced by this plant louse, occur on the upper surface of the 

 leaves of red elm. The interior, as in the case of other plant 

 louse galls, is frequently swarming with aphids in various stages 

 of development. This species is somewhat rare in New York 

 State. 



Vagabond gall (Pemphigus vagabundus Walsh) . 

 This insect produces a rather common leafy deformation. It 

 is simply a peculiar, folded, convolute mass of foliage some 2 

 inches in diameter and near the tips of the twigs. Occasionally 

 these galls are quite abundant. 



Poplar leaf stem gall (Pemphigus populitrans- 

 versus Riley). This species is sometimes very abundant. 

 The galls are oval, about 3/2 inch long, somewhat elongate, with 

 transverse openings, and develop near the middle of the leaf 

 petioles of cottonwood during the latter part of the summer. The 

 poplar is also affected by several allied forms. 



Spruce gall aphid (Chermes abietis Linn.). The 

 presence of this insect is easily recognized by the cone-shaped, 

 many celled galls formed at the bases of young spruce .shoots. 

 These dry, turn brown and open in August, thus allowing the 

 inclosed plant lice to escape. This insect is \videly distributed in 

 New York State and has been responsible in recent years for 

 a number of inquiries accompanied by complaints of injury. 

 This latter is due in large measure to the inability of the affected 

 shoot to continue its growth and, as a consequence, the branches 

 soon become irregular and the tree very unsightly. 



