Februaty, '14] PARKER: SUGAR-BEET ROOT-LOUSE 137 



This paper will deal only with the life history, while technical de- 

 scriptions, studies in sjrtionomy and a discussion of control measures 

 will be reserved for future publication. 



Wingless Viviparous Females — Virgogenia of European Writers 



Early in the spring the full grown, subterranean, wingless, viviparous 

 females which have survived the winter, begin to give birth to living 

 young which also develop into wingless viviparous females. This 

 rapid method of reproduction continues throughout the summer and is 

 checked only by cold weather, lack of food or unfavorable soil con- 

 ditions. A very wet spring may result in the death of all the hibernat- 

 ing lice, while in a dry spring they may feed and develop upon rootlets 

 left in the ground from the previous season until the new crop of beets 

 offers them more attractive food. 



Wmgless viviparous females have been found in Montana upon the 

 following plants: very common upon pigweed {Chenopodium album L.) 

 and sugar beets; common on table beets, foxtail {Hordeum juhatum L.) 

 and salt grass {Distichlis spicata Greene); occasionally upon blue-joint 

 (Agropyron occidentale Scribn.) and dock {Rumex crispus L.); rarely 

 upon wheat, flax, alfalfa, and horseweed {Iva xantMifolia Mutt.). 



Winged Fall Migrants — Sexupara of European Writers 



From midsummer until late fall a part of the young which are pro- 

 duced by the wingless viviparous females develop wing pads and when 

 full grown acquire ■wdngs and fly away. The conditions of the soil in 

 regard to moisture has much to do with the number of winged lice 

 that are produced. If the ground is kept moist or the rootlets of the 

 host plant are succulent, few winged lice are produced, but if the soil 

 becomes dry and the rootlets tough, the production of winged lice is 

 greatly accelerated. In September and October Avhen the beet fields 

 generally become quite dry, the ground is sometimes almost black with 

 the myriads of winged lice that have crawled up from the roots. Doane 

 makes this statement:^ "These winged individuals are the ones that 

 provide for the distribution of the species, for after making their way to 

 the surface of the gromid, they sometimes fly for considerable distances. 

 Having settled at the root of some plant, they soon begin to bring 

 forth living young and thus a new colony, the winter colony, is 

 established. 



In Montana we have not observed this to be true. All of the many 

 winged lice which we have confined in glass tubes have given birth to 

 young which could not possibly start winter colonies. For several 



1 Page 8, Bulletin Xo. 42, Washington Experiment Station. 



