JOURNAL 



OF 



ECONOMIC ENTOMOLOGY 



OFFICIAL ORGAN AMERICAN ASSOCIATION OF ECONOMIC ENTOMOLOGISTS 



Vol. 12 DECEMBER, 1919 No. 6 



THE MIGRATION OF HARMOLITA GRANDIS FORM 



MINUTUM : AN IMPORTANT FACTOR IN ITS 



CONTROL^ 



By W. H. Larrimer and A. L. Ford, Scientific Assistants, Bureau of Entomology, 



West Lafayette, Indiana 



During the spring of 1919, HarmoUta grandis was found to be present 

 in unusual numbers throughout the eastern portion of the great wheat 

 belt. It was evident that should no control measures be used, the 

 infestation might develop into a very serious one within a few j^ears. 



Because of the fact that the spring form of this species cannot migrate 

 long distances (it being for the most part wingless) rotation of crops has 

 been a long approved recommendation for the control of this important 

 wheat pest. A search of the Hterature on this subject failed to reveal 

 any definite data concerning the migratory powers of the spring form of 

 this species. In as much as this has a direct bearing upon the kind of 

 rotation that will effectively control this species, and since the writers 

 have obtained definite data along this Une, they deemed it worthy of 

 puVjlication. 



It is a well known fact that the spring form of H. grandis, although 

 wingless, can migrate short distances by its pedal efforts. It is also 

 generally known that this insect hibernates for the most part in the 

 stubble of the previous year's crop. This means that in case wheat is 

 sown adjacent to the stubble of the previous year's wheat crop, the edge 

 of this field will become infested by the spring form, which comes off the 

 stubble. The second generation individuals which arc winged and strong 

 flyers, can then emerge from this infested strip and infest the entire field 

 and even adjacent fields. It is the intention of the writers to show by 



definite tlata the distance the spring form of this species can migrate and 



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' Published by permission of Secretary of Agriculture. 

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