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This paper is a contribution of Principal Investigators of the Alfalfa Subproject supported 
by an International Biological Program (IBP) sponsored grant, NSF Grant No. GB-34718, 
“The Strategies, Principles, and Tactics of Pest Population and Regulation in Major Crop Eco- 
systems.” 
Subproject Director: E. J. Armbrust 
Principal Investigators: 
Illinois: E. J. ARmBrust and W. G. RuEsINK 
Utah: D. W. Davis 
Nebraska: D. G. Hanway and E. A. DickAson 
New York: R.G.HELGESEN 
Kentucky: B.C. Pass 
Virginia: R. L. PlIENKOWSKI 
California: V.M. STERN 
The authors are grateful for the assistance of Dr. Mervin Nielson, USDA, ARS, Tucson, 
Arizona, who loaned us his personal bibliography. ‘The illustrations used in the cover design of 
this booklet were provided by Dr. G. F. Knowlton, Utah State University. 
Distribution of Spotted Alfalfa Aphid 
Therioaphis maculata 
Prepared by Pest Survey and Technical Support Staff 
Plant Protection and Quarantine Programs 
Animal and Plant Health Inspection Service, USDA 
August 25, 1972 
