18 BULLETIN 436, IT. S. DEPAETMENT OF AGEICULTURE. 



REMEDIAL AND PREVENTIVE MEASURES. 



The control of this msect 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- 

 tihzers, or any other stimulative measures, as has been recommended 

 by Mr. Wilson in his notes upon this species, then the plant wiU 

 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 

 wiU be almost neghgible. 



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 m the ground, even with the surface 

 of each hiU 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 hiU 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. 



