312 AGRICULTURAL APPROPRIATION BILL, 1924. 



CONTROL AND PREVENTION OF SPREAD OF THE MEXICAN BEAN BEETLE. 



Mr. Graf. Any statement we iiiiorht make on our last year's work 

 with the Me.xiean bean hettk' would he largely a statement of the 

 progress of tlie insect, rather than of our own. It is still spreading. 



Mr. Anders<>n. I think you had better begin at the beginning and 

 cive us a history, because we will hear something about it later on. 



GENERAL STATEMENT OF WORK. 



Mr. Graf. 'I'iiis insect is probably Mexican in origin. It has been 

 in the Rocky Mountain region, in, Arizona and Colorado, for about 

 ,50 years. 



In 1920 some specimens were found in Birmingham, Ala., its first 

 appearance in the East. The insect was found to be distributed in 

 13 counties, centering on Birmingham, with an area of about 4,500 

 square miles. The following year 1921 found it in five States, over 

 an area of 4.5,000 s(|uare miles. 



Mr. Anderson. What States did you find it in? 

 Mr. Graf. Alabama, Tennessee, North and South Carolina, and 

 Kentucky, but- the main infestation w-as in the northern part of 

 Alabama, northern Georgia and eastern Tennessee, with just a few 

 counties in the other States. 



At the same time a great many tests were made with various 

 arsenicals in an attempt to develope a control for the insect. It 

 was necessary to work out entii-el}' new dilutions of poisons since 

 humid climate in the East often causes severe plant injury. 



Our standard arsenical, lead arsenate, caused a great deal of 

 injury to the j)lants. We found calcium arsenate and magnesium 

 arsenate w^ere relatively safe; the only trouble with calcium arsenate 

 was that it was unsafe to apply the arsenical strong enough to con- 

 trol the insect. Where many insects are present it is difficult to 

 save the plant with any poison and much additional work is necessary 

 to obtain a safe and sure remedy. 



This year the work on insecticides was continued. Scouting was 

 stopped on account of lack of funds and we have no exact iaea of 

 the mfestation except that it is within about .50 miles of the Ohio 

 River and moving north rapidly. 



This blue line [indicating], which shows the infestation for 1922, 

 is very inaccurate, because we depended on correspondence almost 

 altogether. If the insects spread durino; the past year in the same 

 direction that it spread in the two previous years, it ought to be in 

 WVst Virginia. \\ e are not saying it is in West Virginia. It has not 

 been so re|)orted, i)ut it is continuing its spread very rapidly. 



As far as recommendations for control go, we hesitat<' to recommend 

 magnesium arsenate, because of its injurious eftect on peach foliage. 

 Mr. Andkrsox. What do you mean? 



Mr. (iKAr. It caused much injury to peaches. It ])urns the 

 leaves. 



Doctor Howard. The peach is extremely susceptible. Is a bean 

 as suscei)tible as (he peacli i 



Mr. ditAf. It is to some but not to others. We have always 

 believed that (he soliibU* arsenic contcMit of a poison is what causes 

 the damage, but tlie other chemicals in the insecticide also have some 



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