7-6. BULLETIN" 826, U. S. DEPARTMENT OF AGRICULTURE. 



in the genus by Lichtenstein (1885) and this species has been indicated 

 as type of the genus by Kirkaldy (1905) . Tremulae De Geer is a well- 

 known species but the writer has been unable to obtain ligustrinellum 

 and, in fact, has been unable to learn anything definite in regard to 

 the species. The following conception of the genus, therefore, is 

 based upon tremulae De Geer in view of the fact that ligustrinellum 

 appears to be unknown, and since Aphis populi Fab. was indicated- 

 by Gerstaecker in 1859. 



Characters. — Cornicles absent; wax plates present in the alate forms; stem mother 

 with five-segmented antennas. Alate form with six-segmented antennae which are 

 armed with rather narrow transverse sensoria. Fore wings with the media once forked, 

 hind wings with both media and cubitus present. Forms living in the somewhat 

 crumpled leaves of their host. 



Type (fixed by Gerstaecker, 1859), Aphis populi Fab. 



Genus NEOPROCIPHILUS Patch. 



Plate XIII, A-F. 



1912. NcoprocipUlus Patch, Bui. Me. Agr. Expt. Sta., no. 202, p. 174. 



The genus Neoprociphilus Patch is very close indeed to Prociphilus, 

 the characters which separate it being the somewhat more oval or 

 rounded sensoria and the fact that the sensoria are not ciliate. How- 

 ever, in some of the species of Prociphilus, particularly in the fall 

 forms, somewhat oval sensoria are met with. It is retained doubt- 

 fully. 



Characters. — Stem mother with five-segmented antenna?. Cornicles absent, large 

 wax plates similar to those of Procij:>hilus present. Alate form with six-segmented 

 antenna? which are armed with oval or subcircular nonciliate sensoria. Fore wings 

 with the media simple, hind wings with both media and cubitus present. Sexes small, 

 apterous, and beakless. Oviparous female developing only one egg. 



Forms living free upon their host, the stem mother and following generations in 

 company. 



Type (monotypical), Pemphigus attenuatus O. S. 



Genus PROCIPHILUS Koch. 



Plate XIII, G-N. 



1857. Prociphilus Koch, Die Pflanzenlause, p. 279. 



1857. Stagonia Koch, Die Pflanzenlause, p. 284. 



1875. Holzncria Lichtenstein, Bui. Soc. Ent. Fr. (5) v. 5, p. lxxvi. 



1917. NisMyana Matsumura, S3mopsis of the Pemphigidac of Japan, p. 90. 



Ill 1857 Koch erected his genus Prociphilus with three species: 

 bumeliae Sclirank, erraticus Koch, and gnaphalii Kalt. Later in 

 the work (p. 284) he used xylostei De Geer as the type of the genus 

 Stagonia. This species, xylostei, is in all respects similar to bumeliae 

 and therefore Stagonia becomes a synonym of Prociphilus. In 1875 

 Lichtenstein erected the genus Holzneria with poschingeri Holzner 

 as type. Poschingeri has been considered by many authors as the 

 alternate form of bumeliae. In such case Holzneria must necessarily 



