INSECT ENEMIES OF EASTERN FORESTS sil 
project upwards to a height of 0.75 inch above the leaf surface. These 
galls are toothed along the top, this characteristic accounting for the 
common name of cockscomb gall (fig. 25, 4). To control this aphid, 
apply a spray (see p. 36) as soon as the leaves appear in the spring. 
while the aphids are feeding on the leaf surface and before they be- 
come enclosed in the galls soon to be produced. 
The genus Zetraneura includes two species, 7’. graminis (Mon.) and 
T. ulmisaccula Patch (fig. 25, B), which are sometimes encountered on 
elm. The former attacks American and slippery elms from New Eng- 
FIGURE 25.—Insect galls: A, Cockscomb elm gall caused by Colopha wulmicoia 
(Fitch) on leaf of American elm; B, bladderlike galls caused by Tetraneura 
ulmisacculi Patch on leaves of elm. (Courtesy Maine Agr. Expt. Sta.) 
land west to Missouri and Colorado. The latter attacks wych elm in 
New England. Neither species is of much importance as a pest. 
Gobiashia ulmifusus Walsh and Riley, the red elm gall aphid, is 
found from New England and southern Canada to Colorado on the 
west. It is probably present in all other parts of the country where 
its only known host, slippery elm, grows. Galls produced by the 
species are spindle-shaped and sacklike, and may be 1 inch long. 
TringE PEMPHIGINI 
The species included in the tribe Pemphigini lve exposed on the 
twigs of the host or within curled leaves or true galls on leaves or 
young wood of the winter host. Summer generations are generally 
produced on roots of grasses, herbs, or trees. The stem mothers have 
tour- or five-jointed antennae, the young of the stem mother are winged, 
