The life history of none of these forms is completely known or 
knowledge of the Chaitophorus and the Siphonopliora being confine 
to the period of their appearance upon the foliage m summer. It 
root-louse and the corn plant-louse certainly commence their attac 
in spring, and continue, in some of their stages, throughout tt 
season, the former infesting likewise several grass-like plants wine 
are among the common weeds of corn and sorghum fields, out lat< 
commonly attacking only sorghum, corn and broom-corn. 
Both of these latter species are continuously attended by certai 
abundant ants which assist in their distribution and protect the] 
from their enemies. There is much reason to believe, also, tin 
these ants render them efficient service during the winter by trail 
porting them to suitable quarters for hibernation, and it is probab 
that they spread them about again in spring and place them upc 
the roots of plants suitable for their food. 
Beyond the fact that the corn plant-louse is obviously much mo 
numerous and destructive in fields that have been pre\iously in coi 
or grass, we have at present no clue to preventive or remedi 
measures against these insects; but it is probable that a comple 
knowledge of their life history will enable us to construct a syste 
of rotation which will restrain their multiplication, and keep the 
injuries within due bounds. 
By Dr. Thomas, the application of lime fertilizers to the soil 
recommended for the purpose of preventing injuries by root-lice, b 
apparently more on theoretical than expeiimental grounds. 1. 
fact that one of the sorghum fields at Champaign most infested , 
plant-lice, and in which the older roots were thoroughly deadene 
had been treated to a heavy dressing of superphosphates, mdicat 
that this form of fertilizer, at any rate, would have no lnjurio 
effect upon the plant-lice. There is evident need of careful pi 
systematic experiment with respect to the actual value of the app 
cation of any substance to the ground for the purpose of controlh: 
the root-lice, which shall be sufficiently beneficial to the crop to p 
the expenses of its use. 
