GENERIC CLASSIFICATION OF APHIDIDAE. 73 
Genus RHIZOCTONUS Mokrzecky. 
1895. PMzoctonus Mokrzecky, Horae. Soc. Ent. Ross., v. 30, p. 438. 
The genus Rhizoctonus was erected for ampelinus Mok., a species 
occurring on the vine. Through the kindness of H. F. Wilson the 
writer has been able to examine a slide conta in ing alate forms. 
These, however, are in a very poor condition and it is impossible to 
determine whether or not cornicles are present. The antennae too 
are much distorted. This slide seems to indicate, however, that 
ampelinus is somewhat related to passeriniiSig., an hypothesis which 
is strengthened by the fact that both species hold the wings flat 
in repose. The genus, therefore, is placed here with some hesitation. 
Characters. — Antennee of six segments, -without secondary sensoria and rather thick. 
Fore wings with the media simple. Hind wings with both media and cubitus present. 
Wings held flat in repose. Cauda and anal plate rounded. 
Type (moriotypicstl), Rhizoctonus ampelinus Mok. 
Tribe MELAPHINI. 
The tribe Melaphini is suggestive both of the Pemphigini and of 
the Eriosomatini. It is, however, quite distinct from both. The 
habits more nearly resemble those of the Pemphigini. The tribe 
is placed here but a study of the sexes may show that it really belongs 
to the Hormaphidinae. The typical host group is Rhus, and the 
galls are typically fall galls. 
Characters. — Gall-inhabiting forms. Cornicles absent; antennae of the alate form 
of five or six segments armed with some-what oval or linear transverse sensoria . Sexual 
forms not known. 
The genera may be separated as follows: 
Key to the Genera of the Melaphixi. 
1. Both media and cubitus present in the hind wings 2. 
Only the media present in the hind wings - Aploneura. 
2. Stigma, of four wings pointed on distal portion and extending some distance 
Melaphis. 
Stigma stopping abruptly on distal extremity 3. 
3. Antennae of five segments Xurudea. 
Antennae of six segments Pemphigella. 
Genus APLONEURA, 
Plate XII. A-E. 
1863. Aploneura, Passerird, Aphididae Italicae, p. 78. 
1869. Tetrenema Derbes, Ann. des Sc. Nat. Zool. (5), v. 11, p. 106. 
1848. Baizongii Rondani, Xuovi Annali delle Scienze Natural!, v. 9, p. 35. 
The genus is distinguished quite easily from related one's hj the 
venation of the hind wings, the relation of the cubitus and anal of the 
fore wings, and by the structure of the antennae. The positive determi- 
nation of the insect of Fabricius may cause Aploneura to fall for 
Rondani's name. 
