18 BULLETIN 436, U. S. DEPARTMENT OF AGEICULTUEE. 
REMEDIAL AND PREVENTIVE MEASURES. 
The control of this insect over a wide area can be accomplished 
only by cultural methods, the eradication of its hibernation quar- 
ters, and the destruction of some of its favorite, native and adopted 
grass and weed food plants. In smaller areas, consisting of only 
a few acres, a certain degree of success can be expected from the 
use of arsenate of lead as a spray. Several experiments were tried, 
using different kinds of repellents, but without any great amount of 
success. 
The greatest damage is done to the plant just as it is coming through 
the ground, because at this time it is more tender and attractive to 
the beetles and also is less resistant to insect attack. If, there- 
fore, the growth of the plant is stimulated by good cultivation, fer- 
tilizers, or any other stimulative measures, as has been recommended 
by Mr. Wilson in his notes upon this species, then the plant will 
have an excellent chance in spite of the flea-beetles. If the numbers 
of the beetles are also lessened by the cleaning up of hibernation 
quarters and the eradication of breeding places, the plants will have 
a still greater chance of reaching maturity, and finally, if the plants 
are sprayed by arsenate of lead, as will be shown later, the damage 
will be almost negligible. 
REPELLENTS. 
While located on a ranch south of Holtville, Cal., in April, 1910, 
the writer undertook to determine the value of several volatile oils 
and also of naphthalene balls, as repellents for this beetle. The 
oils used were those of eucalyptus, citronella, and pennyroyal. A 
small piece of cotton was placed in the ground, even with the surface 
of each hill of corn treated, and was moistened with the oil each 
morning for five days, while the naphthalene balls were utilized by 
placing a single ball beside a hill of corn. Two rows were treated 
with each of the four remedies used and every third row was left 
untreated as a check row, the idea being that if the corn could be 
protected for a few days it would reach a stage of growth in which 
it would be able to withstand an attack from the flea-beetles. The 
results of this experiment may be summarized as follows: The 
naphthalene balls and the oil of eucalyptus were found to act in no 
way as repellents of this beetle. The rows treated with the oil of 
citronella were damaged the least by the flea-beetles, while the rows 
treated with the oil of pennyroyal were damaged only slightly. 
However, since the cost of these oils and the time taken in applica- 
tion were found to be prohibitive from an economical standpoint, and 
since the results were not conclusive, the use of these repellents 
can not be recommended. 
