142 MISCELLANEOUS STUDIES 



versus Riley. All of these species, during at least a part of their life 

 cycles, infest various species of Populus, where they form more or less 

 distinctive galls. 



KEY TO FUNDATRIGENIAE 27 



1. Secondary sensoria present only on III. Galls formed on leaf petioles, with a 



transverse opening on the outside of the curve populi-transversus Eiley 



Secondary sensoria on other segments as well as on III 2 



2. Secondary sensoria on III to VI inclusive. Galls formed by the twisting of 



the petiole with an oblique opening on the inside of the curve. 



populi-caulis Fitch 



Secondary sensoria on III and IV. 2 Gall formed on the under side of the 



leaves, being more or less elongate and opening on the upper side. 



betae Doane 



164. Pemphigus betae Doane 



Doane, Ent. News., vol. 11, p. 390, 1900 (orig. desc.). 



Clarke, Can. Ent., vol. 35, p. 248, 1903 (list). 



Davidson, Jour. Econ. Ent., vol. 2, p. 299, 1909 (list). 



Davidson, Jour. Ecou. Ent., vol. 3, p. 372, 1910 (list). 



Williams, Univ. Neb. Studies, vol. 10, p. 92, 1910. P. balsamiferae n.sp. 



(desc. fundatrigenia). 



Essig, Pom. Jour. Ent., vol. 4, p. 299, 1912 (list). 

 Maxson, Jour. Econ. Ent., vol. 9, p. 500, 1916 (note). 



Becords. Beta vulgaris; San Francisco Bay region, Monterey County, Sacra- 

 mento Valley. (Rumex spp., Chenopodium spp., etc.?) 



Under the name P. betae Doane, Clarke, Davidson, and Essig have 

 reported a species of aphid infesting the roots of sugar beets, dock, 

 Chenopodium, and other plants throughout California. 



Originally this species was described from specimens taken on 

 sugar beet in Washington, but later 29 it was proven that a species 

 forming elongated leaf galls on Populus balsamifera in the spring 

 migrated to beets, and was identical with this species. In 1916 Maxson 

 (cited above) states that his investigations point to the fact that in 

 Colorado there are more than one species of Pemphigus attacking the 

 sugar beet, one of which is this species that forms the elongate leaf 

 gall on poplar in the spring, and which is known now as P. betae 

 Doane. 



27 At present only a key to the alate migrants or fundatrigeniae occurring in 

 galls on poplar is given. It is hoped that later, keys to all forms may be formu- 

 lated. At present, however, the life histories of the species are not sufficiently 

 known. 



28 The sexupara or alate migrants from beets to poplars have secondary sen- 

 soria on III to V inclusive. These form no galls on poplar, however. 



29 Parker, The life history of the sugar-beet root louse, Jour. Econ. Ent., vol. 

 7, pp. 136-141, 1914; 



Gillette, Notes on some Colorado aphids having alternate host plants, Jour. 

 Econ. Ent., vol. 8, p. 97, 1915. 



