1/8 ARTHUR G. VESTAL. 



are mostly grassland forms, since ground conditions are essen- 

 tially the same in both situations. In closed forest and moist 

 herbaceous associations species and individuals are less numerous, 

 are not confined to the ground stratum, and are more intimately 

 associated with vegetational conditions. Grasshopper species 

 can be arranged according to gradients of environmental factors 

 (Fig. i, p. 156). 



Grasshopper succession is incidental to the development of 

 vegetation. The change is not only one of species, but of habits 

 as well. 



Grasshopper species have in general the geographic range of 

 the types of associations which include the necessary physical 

 and vegetational conditions. The ranges of many species are in 

 agreement with the areas of vegetation provinces. Species of 

 least definite local distribution are widespread geographically. 



Seasonal differences in time of activity of grasshopper species 

 are marked. This is probably partly due to antagonistic 

 influence of other animals. Seasonal and local distribution 

 are interrelated. Species of indefinite local distribution have 



also least definite time distribution. 

 UNIVERSITY OF COLORADO, 

 April 5, 1913. 



VI. ACKNOWLEDGMENTS AND BIBLIOGRAPHY. 



The privileges of the University of Michigan Biological Station 

 at Douglas Lake were extended to the writer during the summer 

 of 1912, for which he is grateful to the Director, Professor Jacob 

 Reighard. The writer is indebted also to Miss Alvalyn E. 

 Woodward, who has furnished data concerning grasshopper 

 species not taken by the writer; to Dr. H. A. Gleason, who has 

 been of great assistance in the study of the plant associations; 

 and to Dr. V. E. Shelford and to Dr. M. M. Ellis, who have read 

 the manuscript. 



BIBLIOGRAPHY. 

 Adams, C. C. 



'06 An Ecological Survey in Northern Michigan. Report from the University 

 Museum, published by the State Board of Geol. Surv. as a part of the 

 Report for 1905. Lansing. 



'08 An Ecological Survey of Isle Royale, Lake Superior. Report from the 

 University Museum, published by the Geol. Surv. Lansing. 



