TRIBES OF APHIDIDAE 71 
itas a section. Mordwilko (1908) first suggested the term Pemphigina 
as a group. 
Morphological characters. Antennae usually short; sensoria oval 
or ring-like as in the preceding group, but the annuli are usually incom- 
plete not extending around the segment; in Hormaphidini the annuli 
are complete. Media usually simple and not branched; veins of the 
hind wings usually arranged in a triradiate fashion. Gland areas less 
conspicuous, the facets usually arranged irregularly and are smaller 
and more crowded. Cornicles wanting. Fundatrices with only four 
segments to the antennae. 
Biological characters. The Pemphigina include all the true gall 
forms, migrating to various habitats for the summer but returning to 
their favorite plants in the fall for hibernation and the gall genera- 
tions. 
KEY TO THE TRIBES OF THE PEMPHIGINAE 
1. Antennae of the migrants and spuriae with six segments; cauda and anal plate 
NOLDODVAOUS Sie) a i 18. Tribe PEMPHIGINI 
—Antennae of migrants and spuriae with three to five segments; cauda and anal 
joey Olonaoisig 5 ia 6 19. Tribe HORMAPHIDINI 
18. Tre PEMPHIGINI 
Morphological characters. Antennae in migrants and spuriae 
composed of six segments; usually very short; sensoria transversely 
oval or as incomplete annuli, the ends of which do not meet or fuse. 
Media usually simple; cubitus and anal approximate at origin; veins 
of hind wings usually arranged in a triradiate fashion. Cornicles 
wanting, and cauda inconspicuous. 
Biological characters. ‘This tribe includes practically all the gall 
forms, that produce typical aphidian galls. The favorite food habitat 
for hibernation and for the gall generations appears to be Populus. 
19. Trine HORMAPHIDINI 
Osten Sacken, 1861, Stett. Ent. Zeit. Vol. 22. Sub Hormaphis (genus). 
Borner, 1908, Monogr. Cherm. Sub Hormaphidinae (subfamily). 
Mordwilko, 1908, Acad. Imper. Vol. 13. Sub Hormaphidina (group). 
Tullgren, 1909, Ark. Zool. Vol. 5. Sub Hormaphidina (tribe). 
Osten Sacken (1861) recognized the first genus of the present 
tribe. Borner (1908) considers the group to be of subfamily value and 
names it Hormaphidinae. Mordwilko takes it as a group under the 
subfamily Pemphiginae. Tullgren (1909) considers it as a tribe. 
Morphological characters. Antennae of migrants and spuriae 
with three to five segments; sensoria annulate and forming complete 
