Pemphigus betae

Pemphigus betae Doane

This insect is a native of the Rocky Mountain region, and is a rather general feeder upon the roots of plants during the summer season. The goosefoot family, especially sugar beets, garden beets and mangel wurtzels, are favorite food plants. Among our native plants and weeds, we have found this louse common upon the roots of Aster, goldenrod (Solidago), Iva xanthifolia, and lambsquarter, Chenopodium. While it does not seem necessary for this insect to take on a fall migratory habit, still, as near as we have been able to estimate, about one-half of the lice acquire wings during September and October and leave their summer hosts and fly to the cottonwoods. Apparently, only a small percentage ever find the desired host. In beet-growing sections it is common for these lice to fly in countless millions, like great swarms of ants, for- more than a month during the warmer portion of the day. Since the fall of 1910 we have known that this louse migrates to the cottonwoods, in large numbers in the fall to deposit the sexual males and females, but not until the past summer has it been definitely determined in what form this species appears upon the cottonwoods early in the summer. Mr. Asa C. Maxson, in charge of the experimental work in the Longmont district for the Great Western Sugar Company, who has been a collaborator with us in some plant louse studies, has succeeded the past summer in determining the form of gall produced by this louse upon the cottonwood leaves and in successfully colonizing the lice in large numbers upon the beets and in rearing from these colonies, the sexuparae. We extract from a report by Mr. Maxson upon his work as follows: "On May 4th . . . the larvae were located upon the upper side of the leaf which was light in color where the larvae were feeding, and showed a depression which, as it grew larger, entirely inclosed the insect and formed a gall on the under side of the leaf. This form of gall is produced by Pemphigus balsamiferae Williams." 

Many observations by the writers tend to confirm the conclusions reached by Mr. Maxson whom we congratulate on the excellent life history work that he has done on this insect, which is one of the worst pests that the sugar beets have to contend against in the Rocky Mountain States. 

It seems probable that Parker, in Journal of Economic Entomology, 1914, page 139, hit upon the correct gall for this louse, but referred to it on page 141 as by populicaulis Fitch, which produces a globular gall upon the petiole of the leaf. Furthermore, this gall occurs in the Middle and Eastern States, while P. betae seems to be strictly a Western species. 

Notes on some Colorado aphids having alternate food habits