64 REPORT OF No. 19 



terior contains numerous aphids in July and June. The gall is 1.5-2 cm. 

 long by 1 cm. high.. Occasionally a number occur on a leaf side by side. 

 It is constricted near the base. Occurs on American Elm (Ulmus Ameri- 

 cana), Common. 



Spiny Witch-Hazel Gall (Hormaphis spinosus). 

 This gall is round, covered with long spines. It is a deformation of 

 the fruit bud. The spines are covered with little clusters of hair like those 

 on a cactus leaf. In it are many small aphids, brown in color. The open- 

 ing to the gall is at the base, near the stem of the gall by which it is joined 

 to the branch. Green in summer, woody and hard in winter. Occurs on 

 Witch-Hazel (Hamamelis vir giniana) . Common. 



Witch-Hazel Cone Gall {Hormaphis hamamelidis) . 

 This gall is cone-shaped, about 5 m.m. in length by 3 m.m. in diam- 

 eter. It occurs on the upper side of the leaves, with the opening through 

 a small hole in a slightly projecting cone on the under side of the leaf. The 

 opening is about 5 m.m. in diameter. The gall is hollow, containing num- 

 erous aphids which are white in color. Occurs on Witch-hazel {Hamamelis 

 virginiana) . Common. 



Poplar Stem, Gall {Pemphigus populicaulis) . 

 An irregularly spherical gall developed at the junction of the petiole 

 and blade of leaf. The opening is as wide as the gall and is at one side of the 

 base of the pouch. It is hollow, about 11 m.m. in diameter, ^containing 

 large numbers of aphids. Occurs on Cottonwood {Populus deltoides). Com- 

 mon. 



Hickory Cone Gall {Phylloxera Caryae-fallax). 

 This is a cone-shaped gall about 3 m.m. in diameter which occurs 

 rather uncommonly on Hickory in this district. The gall is on the upper 

 surface of the leaf, the opening being in a smaller cone upon the under sur- 

 face. The gall is monothalamous, and contains numbers of small white 

 aphids. It is green in color, and the opening is fringed with hairs. Oc- 

 curs on Shell-Bark Hickory {Carya alba). Not common. 



Vein Gall on Hickory {Phylloxera caryaevenae). 

 This gall consists of a fold of the main veins running from the mid- 

 rib to the edge of the leaf. Above it is ribbed by the vein running along 

 it. It is 5 m.m.-l cm. in length and 1-1.75 m.m. wide and 1.5-3 m.m. 

 high. The galls are red. From the ventral side they appear as slits along 

 the vein, lined with white thick hair. The gall is hollow and contains eggs, 

 small aphids and a stem mother. The eggs are oval and transparently 

 white and the gall is grooved inside, evidently for the purpose of holding 

 them. The galls begin to appear in May, and are mostly empty by August. 

 The larvae, according to Pergande, conceal themselves in cavities of the 

 bark, or in deep depressions in the trunk and stem after leaving the gall, 

 where they feed upon the juices of the tree. Occurs on Shell-Bark Hickory 

 {Caryd alba). Not common. 



Cottonwood Midrib Gall {Pemphigus sp.) 

 A somewhat elongated pouch-like gall of aphid origin growing on the 

 midrib of the leaf of the cottonwood, about halfway between the base and 

 the apex of the leaf, and never on the leaf at the junction of the petiole and 

 blade like P. populicaulis . Also instead of being irregular globular as is the 

 latter, this gall is pouch-shaped, about 1-1.5 cm. broad. Occurs on Cot- 

 tonwood {Populus deltoides). Common. 



