500 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



SOME UNPUBLISHED NOTES ON PEMPHIGUS BETiE 



DOANE 



By Asa C. Maxson, In charge of Insect Investigations for the Great Western Sugar 

 Company, Longmont, Colo. 



In April, 1912, the writer began a study of the Hfe-history and habits 

 of the sugar beet root-louse, P. beta Doane, in cooperation with the 

 Colorado Experiment Station. The work was done at Longmont, 

 Colo., the funds being furnished by the Great Western Sugar Company 

 in whose employ the writer has been since 1910. 



While the main facts in connection with the life-history of this 

 insect have been given by Gillette and Bragg, Journal of Economic 

 Entomology, vol. 8, no. 1, p. 97, there still remain a number of un- 

 published observations which have a bearing upon the life-history 

 and habits as well as the control of this pest. 



Hibernation of Apterous Form 



In order to ascertain to what extent the apterous lice live over from 

 season to season in the soil of old beet fields, three fields were examined 

 during the second week of April. At this time the spring field work 

 had not begun and no weeds had started in the fields. The examina- 

 tion was made by digging holes about 10 inches in diameter and from 

 8 to 10 inches. deep. The soil from these holes was carefully examined 

 by crumbling it with the fingers. 



In field No. 1, which had grown sugar beets continually for at least 

 6 years, holes were dug at both ends and in the centre. Of the 101 

 holes dug in this field the soil from 52 per cent yielded living root-lice. 

 The east end of the field is higher and drier than the west end. Sixty 

 per cent of the diggings in this part of the field yielded living lice while 

 but 25 per cent of those at the west end produced lice. In the centre 

 section of the field 55 per cent of the diggings produced lice. 



Field No. 2 grew its first crop of sugar beets in 1911, the previous 

 crop being alfalfa. The soil from 56 per cent of the holes dug in this 

 field yielded living lice. 



Field No. 3 grew its first crop of beets in 1911, also, following a crop 

 of barley. In the soil from 76 per cent of the holes dug in this field 

 living lice were found. 



Hibernating Lice as a Source of Crop Infestation 



In the determining of this point three cages 8x3x3 feet, consisting 

 of a light frame work covered with muslin, were used. These cages 

 were placed at the east end of field No. 1. They were placed end to 



