254 B. H. GRAVE- 



ACKNOWLEDGMENTS 



I wish to acknowledge my indebtedness to Prof. S. K. Loy of 

 the Department of Chemistry at the University of Wyoming, 

 who collected living material and sent it to me, making it possible 

 to complete the study of the life history. 



I am indebted also to Prof. L. O. Howard and his staff, who 

 identified the species and encouraged me to finish the work; 

 to Prof. Aven Nelson of the University of Wyoming, who de- 

 termined the species of trees upon which the larva feeds. 



During the present summer Prof. A. S. Pearse and Prof. W. S. 

 Marshall at the University of Wisconsin have given me every 

 convenience and shown me every courtesy, for which I wish to 

 express appreciation. 



