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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
and a total effectiveness of 77 per cent for the two pounds of arsenate 
of lead. On the other hand nearly 6 per cent of the plants treated 
with one pound of lead were badly damaged as against 1 per cent for 
the plants treated with two pounds. The number of replants made up 
to this inspection is practically identical. Later inspections, however, 
show a decided advantage for the treated plots, only 2 per cent being 
replanted whereas the check plot showed 17 per cent replants. The 
term sun scalded is used to express an unknown factor which caused a 
burning on the tips of the leaves and which might be attributed to the 
poison used, especially in light of the fact that this condition was nearly 
twice as bad in the plants treated with two pounds as it was in the 
plants treated with one pound, but for the following facts, some of the 
plants in the check plot were also badly scalded and an adjacent field 
set on the following day which received no treatment was sun scalded 
worse than the treated plots. 
In view of these experiments our recommendation to the farmers is 
that the plants should be dipped in arsenate of lead, 1 pound powder or 
2 pounds paste, to 10 gallons of water. 
THE LIFE HISTORY OF THE POTATO LEAFHOPPER 
(EMPOASCA MALI LE BARON) 
By F. A Fenton and Albert Hartzell, Iowa State College, Ames, Iowa 
The potato fields of Iowa and the surrounding states have suffered 
severely from burning for several years until this condition has become 
a seriously limiting factor in the production of this crop. Dr. Ball 1 
has previously demonstrated that the potato leafhopper was responsi¬ 
ble for this condition and has aptly termed the disease “hopperburn.” 
This discovery made the control of the leafhopper the most important 
problem in connection with potato production. 
In order to control this insect it was first necessary to know its life 
history on potato, of which little was known, owing principally to the 
fact that these hoppers were so minute, active, and difficult to keep 
alive under artificial conditions. The problem of its life cycle was 
primarily one of the proper technique. Much time was therefore 
spent in perfecting methods and devices for keeping these insects under 
observation. The methods employed at the outset were only partly 
successful but later were improved with satisfactory results on all 
important phases of the study. 
Climatic Factors 
The season of 1919 was abnormal in the excess of early precipitation 
followed by exceedingly high temperatures. There were two long 
1 Science, N. S., Vol. 48, Aug. 1918, p. 194. Jour, of Econ. Ent., Vol. 12, No. 2, 
1919, pp. 149-154. 
