ACKNOWLEDGMENTS 
The author gratefully acknowledges the invaluable assistance 
of many of his colleagues in the Forest Insect Branch of the 
USDA Forest Service in the preparation of this publication. He 
is also greatly indebted to the following individuals for their 
helpful reviews of different sections of it: Dr. A. E. Brower, 
Maine Forest Service; Dr. R. L. Giese, Purdue University; Dr. D. 
M. Benjamin, University of Wisconsin; Dr. R. F. Anderson, Duke 
University; Dr. Jack L. Krall, State University of New York 
College of Forestry at Syracuse; Dr. R. T. Franklin, University 
of Georgia; Dr. C. E. Atwood, University of Toronto, Canada; 
Dr. J. A. Slater, University of Connecticut; Dr. John A. Davidson, 
Dr. T. L. Bissell, and Dr. F. E. Wood, University of Maryland; 
Dr. D. L. Collins and Dr J. A. Wilcox, New York State Museum 
and Science Service, Albany, New York. Finally, he wishes to 
make acknowledgement to the Connecticut Agricultural Experi- 
ment Station, Illinois Natural History Survey, and Duke School 
of Forestry for the loan of many photographs for illustrations. 
LIBRARY OF CONGRESS CATALOG NO. 76—607316 
