122 
Fig. 34. Imple¬ 
ment used in plac¬ 
ing- carbon bisul- 
fid in soil to kill 
root-lice: a, tin 
tube; b, piston. 
the whole is then thrust into the ground as described above. The 
piston is then removed, the required amount of carbon bisulfid 
poured in, the tin tube removed, and the hole plugged up. As 
carbon bisulfid is inflammable and, when mixed with air, more or 
less explosive, care should be taken not to have the least spark 
of fire about when using it. It may be obtained from any drug¬ 
gist for 20 to 35 cents a pound, but when needed in large quanti¬ 
ties a grade equally effective as a fumigant may be obtained from 
E. R. Taylor, Penn Yan, N. Y. for io cents a pound when or¬ 
dered in quantities of 50 or 100 pouhds. 
Cultural Methods .—When a field of asters has been badly in¬ 
fested with the corn root-aphis, it is well to rotate, planting the 
field in some crop not attacked by the root-aphis. So far as is 
known, the aster and plants closely related to it are the only cul¬ 
tivated flowering plants attacked bv this aphis, so that any other 
flowering plant may be used in the rotation. 
If rotation is impracticable, much can be done towards eradi¬ 
cating the lice by thoro fall plowing. As the object is to dis¬ 
turb the ant nests, where the aphid eggs then are, the later it is 
done the less likely is it that the ants will be able to collect the 
eggs again; and if the winter exposure is not fatal to these scat¬ 
tered eggs, the young hatching from them will starve in spring, 
since they cannot reach the roots of their food plants without the 
aid of the ants. 
Scale Insects 
Cocci dee 
Many species of scale insects infest flowering and ornamental 
greenhouse plants, particularly the orchids, palms, tropical trees 
(in greenhouses), and ferns. In Illinois fifteen species have been 
