ECOLOGY OF ISLE ROYALE. 157 



THE COLEOPTEKA OP ISLE ROYALE, LAKE SUPERIOR, AND 



THEIR RELATION TO THE NORTH AMERICAN 



CENTERS OP DISPERSAL. 



BY DR. CHAS. C. ADAMS. 



1. Introductory Note. 



The beetles secured in 1905 by the Museum expedition were collected 

 during July and August by various members of the party. We are 

 indebted to Prof. H. P. Wickham, of the University of Iowa, Iowa City, 

 for the determination of most of the species; the remainder were deter- 

 mined by Mr. E. A. Schwarz, of the U. S. National Museum, through 

 Dr. L. O. Howard and Mr. E. S. Titus. To these gentlemen we wish 

 to express our appreciation for these favors. Mr. A. B. Wolcott has 

 kindly furnished certain records of distribution, as indicated in the text. 



The field notes and collections were largely miade by Dr. H. A. 

 Gleason; some were made by the writer; and specimens were also col- 

 lected by B. P. Savey. The geographic range of all the species taken 

 is given in some detail, as a basis for geographic conclusions. Time 

 limitations have prevented a full discussion of these. 



The geographic relations of the fauna have been discussed in more 

 than customary fullness. The entire subject of the geographic rela- 

 tions of the North American beetle fauna had to be gone over; and 

 as the work advanced, it became evident that a general account of these 

 faunal relations was desirable from a standpoint somewhat different 

 from that generally expressed. Undoubtedly many important papers 

 and statements have been overlooked, so that it will be desirable for 

 others to further extend this treatment of the subject. 



Attention should also be called to the fact that in the past studies of 

 the distribution of insects have been largely irrespective of their 

 habitats, associations and such ecological relations. Tifhis has been 

 one of the many defects of distributional studies, as it is of the present 

 study. It is for this reason that an attempt is made to briefly discuss 

 the habitat relations and successions of beetle associations. Life 

 history, food habits and other ecological phases need detailed investiga- 

 tion and discussion so that all these phases can be related to the causes 

 and conditions which affect distribution. The economic advantage of 

 a knowledge of the laws of succession of beetle associations has largely 

 been neglected, but ultimately must become one of the main general 

 principles in much economic practice. This will probably become more 

 conspicuous when forests assume a higher value, and the relation of 

 beetles to reforestation, etc., demands careful attention. 

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