!;wigs, led us to test the hypothesis of a migration between 
;hese plants. These experiments, persistently repeated, were, 
lowever, quite without result. The corn lice inclosed in 
lutumn under bell jars with fresh apple twigs neither bred nor 
ed upon them, and invariably perished. Similar experiments 
lave not been made, however, with either grass or wheat, al- 
hough the aerial louse has been found in fall upon both, 
besides a repetition of these and si miliar experiments, the 
nost promising still to be made are those for the transfer of 
successive generations of the winged root lice in June and July 
o the leaves and springing tassels of corn and sorghum. 
ECONOMIC SUGGESTIONS. 
As long as the connection between root and aerial forms 
emains in doubt, all economic discussion must be of a pro- 
isional and tentative character. Some observations and ex- 
leriments on the root louse are, however, worth reporting. 
In the first place, a long list of observations in the field in 
arly spring unite in showing that the corn-root aphis takes 
ts start only in fields where it occurred the year before, and 
hat such fields are, as a rule, most likely to suffer severely 
rom the attack. The early evolution of a partly winged 
>rood provides, however, for so general a dispersal that the 
xpedient of rotation of crops can have only a secondary 
r alue. 
Secondly, the fact that the plant-louse eggs hatch, as a rule, 
ome days in advance of the growth of corn in the fields (usually 
i week or more before corn planting) and that in the meantime 
he lice are dependent on young weeds in the earth, gave the 
lint for some starvation experiments tried in two successive 
ears. From these we learned that young lice just hatched will 
►erish within five days if deprived of food, whether attended by 
jits or not. It seems possible, consequently, that their num¬ 
bers might be greatly diminished in early spring by such a 
borough stirring of the soil with disk harrows or other similar 
pparatus, as would keep down the sprouting herbage in the 
orn field. Any treatment of the field the preceding summer or 
ill which should diminish the number of seeds of pigeon grass 
»r smartvveed maturing in the corn would diminish likewise the 
hances of survival of young root lice the following year. I am 
old that these conditions are agriculturally manageable, and 
ave arranged for field experiments to test these methods. 
A simpler and perhaps more promising expedient is based 
pon the care of the eggs of the common small brown ant, so 
[•equently referred to. The attention which these eggs receive 
>oth in winter and spring makes it seem likely that the care of 
he ants is essential, and as these insects become torpid early, 
arely working beyond November 1, it seems quite likely that 
xte fall plowing of fields infested by them and their guests, the 
oot lice, to be followed possibly by harrowing, would so break 
