2 FARMERS’ BULLETIN 595. 
of a good application of an insecticide is another strong argument 
in its favor. Hand worming, even of the best, has many objections; 
for instance, eggs are not picked off, many small worms are over- 
looked, and, lastly, during the hot hours of the day large worms 
crawl down into the “ruffles” near the bases of the leaves, and 
a considerable number are thus overlooked. On the other hand, 
a thorough application of an insecticide will kill practically every 
hornworm—except those very nearly full grown—within two or 
three days, and will also continue to Jill the young worms that 
hatch several days after the application. In short, hand picking has 
only an immediate effect in lessening the worms, whereas the applica- 
tion of an insecticide usually continues to kill over a period of several 
days. Cheapness is another point very greatly in favor of an insec- 
ticide as compared with hand picking. The cost of keeping an acre 
of tobacco hand wormed in a year when worms are plentiful is 
variously estimated at from $6 to $10. A like number of worms can 
be killed with Paris green at a cost of not more than $2 per acre, and 
with arsenate of lead at a cost of from $3 to $5 per acre. 
INJURY TO TOBACCO BY THE USE OF PARIS GREEN. 
Although Paris green has been in general use upon tobacco in 
many localities of Kentucky and Tennessee for more than a decade, 
yet, on account of its very frequent serious injury to tobacco, many 
growers use it only after it becomes too costly to keep the worms 
off the tobacco by hand picking. Occasionally dosages of 2 and even 
24 pounds are applied without visible injury. On the other hand, 
unfavorable weather conditions may cause dosages of 1 to 14 pounds 
to burn seriously. In 1912 several fields in the vicinity of Clarks- 
ville, Tenn., were injured in amounts varying from 10 to 25 per cent 
of the gross value of the crop. The usual loss, however, is not greater 
than 4 or 5 per cent. 
Paris green injures tobacco in two ways: First, by causing dead, 
burned areas upon the leaves, where the powder has been collected 
by the dews or washed down by the rains; second, by weakening 
the leaf at the stalk. Light rains wash the insecticide into the axils 
of the leaves, and the result is that many leaves drop off before 
cutting time or become so weakened that they drop off when the 
plant is cut. Although such leaves are not a total loss, for they are 
collected and cured, yet they are a partial loss, for they lack weight 
and elasticity. 
ADVANTAGES OF THE USE OF ARSENATE OF LEAD. 
Arsenate of lead causes none of the injury just mentioned. Ex- 
periments performed under the direction of the senior writer show 
that powdered arsenate of lead may be put on a fresh sucker wound 
