GENERIC CLASSIFICATION OF APHIDIDAE. 83 
generations often developed. Cornicles often reduced to mere ringlike openings or 
entirely absent. Sexual forms small and apterous but with fully developed beaks. 
Oviparous female laying several eggs. 
Key to the Tribes or the Hormaphidinae. 
1. Aleyrodiform generations developed 2. 
Aleyrodiform generations not developed Oregmini. 
2. Cornicles absent; insects usually gall formers Hormaphidini. 
Cornicles usually present; insects usually not gall formers Cerataphidini. 
Tribe HORMAPHIDINI. 
Members of this tribe are distinguished easily from those of other 
tribes in that the cornicles are absent and aleyrodiform generations 
are developed. These remain more or less quiescent upon the 
foliage. Some different forms of the species are often gall pro- 
ducers. All secrete wax from special pores. Considerable variation 
is met with in the development of the aleyrodiform generations. 
Sensoria of the alate forms are usually narrow and annular. 
Only two genera are so far recorded. 
Key to the Genera of the Hormaphidini. 
Antennae of the alate forms composed of three segments, hind wings with 
only the media present Hormaphis. 
Antennae of the alate forms composed of five segments, hind wings with both 
media and cubitus present , Hamamelistes . 
Genus HAMAMELISTES Shiiner. 
Plate XIV, T-X. 
1867. Hamamelistes Shimer, Trans. Am. Ent. Soc., v. 1, p. 284. 
1896. TetrapMs Horvath, Wien. Ent. Zeit., v. 15, p. 6. 
Shimer included two species in this genus, spinosus Shimer and 
cornu Shimer. The latter species, as suspected by him, is a syno- 
nym of Jiamamelidis Fitch. This species has been made the type 
of Hormaphis. 
Characters. — Cornicles absent. Stem mother with four-segmented antennae. Aley- 
rodiform generations developed. Alate form with five-segmented antennae which 
are armed with numerous annular sensoria. Wings held flat in repose; fore wings 
with the media simple; hind wings with both media and cubitus usually present; cauda 
knobbed, anal plate bilobed; wax-secreting areas abundantly present in the 
apterous forms. Sexes small and apterous but with beaks developed, oviparous 
female laying several eggs. 
Forms living in galls upon the leaves or scale-like on the leaves or twigs. 
Type (one unquestioned species), Hamamelistes spinosus Shimer. 
