578 
Journal of Agricultural Research 
Vol. XIV No. 13 
Dr. C. P. Gillette also informed the writer that Mr. Paddock sent 
him material from Texas collected from turnip roots on February 13, 
1914, and that the species is the same as that which attacks crucifers 
in Louisiana. Mr. L. C. Bragg has collected the species from watercress 
(Roripa sp.) near Fort Collins, Colo. Mr. J. J. Davis, of the Bureau 
of Entomology, has written that several years ago he received a 
species of Pemphigus collected on curly turnip ( Brassica rapa) at Green¬ 
wood, Miss., which seems to agree with the one under discussion. 
It is the purpose of this paper to present the results of investigations 
carried on at Baton Rouge regarding the life history and habits of the 
species, together with records from other points in Louisiana and from 
other States. These results indicate that the species of Pemphigus that 
feeds on the roots of crucifers is identical with the well-known Pemphigus 
populi-transversus Riley, which causes galls on the leaf petioles of some 
of the poplars or cottonwoods ( Populus spp.). Fortunately, it has been 
possible to have these notes accompany descriptions of the various 
stages made by Dr. Gillette. 
HISTORICAL REVIEW 
While Pemphigus populi-transversus has been often referred to by 
entomological writers since Riley described the species in 1879 (j, p . 
15-16; pL 2 y fig. 5, a-c), these references have been brief and for the 
most part have been limited to records of the occurrence of the species 
in some State or particular locality and a few words regarding bibliog¬ 
raphy and the previously recorded hosts and distribution. Such refer¬ 
ences are mentioned under “Distribution and hosts” on page 580. 
In works in which insects are treated especially from an economic 
standpoint there are several references to the species and its gall. In 
1890 Packard (5, p. 434) mentioned it in his work, “Insects injurious 
to forest and shade trees.” Bruner (6, p . 218, fig. 57), included it in 
an article entitled “ Insect enemies of ornamental and shade trees grow¬ 
ing in cities and parks,” which was published in 1893 in the Annual 
Report of the Nebraska Horticultural Society, and again mentioned it 
(jj) in an article on aphids which appeared in The Nebraska Farmer 
in 1901. Lintner (9, p. 361-362) included it in his Thirteenth Report 
of the State Entomologist of New York, published in 1898, and stated 
that it had been abundant on Populus monilifera in Washington Park, 
Albany, N. Y., during 1896 and 1897. Felt (14, p . 247, 620 , 635-636 , 
pi. ii, fig. 15 , 16) in his work, “Insects affecting park and woodland 
trees,” published by the New York State Museum in 1906, also referred 
to its abundance in the vicinity of Albany and gave colored figures of 
the gall. Baldwin (21, p. 208) referred to it in the Fifth Annual Report 
of the State Entomologist of Indiana in 1912 and gave two original 
illustrations of the gall. 
