AN INTRODUCTION TO THE STUDY OF ROCKY 

 MOUNTAIN BEES 



By T. D. A. Cockerell and W. W. Robbins 



The Rocky Mountain bee fauna is not only remarkably rich and 

 interesting, but in spite of many years of collecting it continues to yield 

 numerous undescribed forms. Among the species described the nesting 

 habits are known only in a few cases, and there is an immense field for 

 interesting research into the biology of these insects. Tables for the 

 separation of many of the species have been published but there has 

 existed no quite serviceable modern work for the determination of the 

 genera, and consequently the beginner has been discouraged at the out- 

 set. Nothing can be written which will make the study of bees easy, 

 in the sense of absolving the worker from attention to numerous minute 

 details or substituting anything for his critical judgment; but it is hoped 

 that the present paper will at least make it possible for him to proceed, 

 supposing him to be reasonably intelligent and industrious. 



There is given first a summary of the classification adopted, in which 

 most of the genera are distinguished. As an appendix to this follows 

 a very brief abstract of Robertson's classification, which is of great value, 

 but unfortunately inadequate, being based wholly on Illinois species. 

 Finally there is offered an artificial key, which can be used by one unfa- 

 miliar with the classification, or the place in the system of the specimen 

 in hand. The numerous illustrations of venation include nearly all 

 the local genera, and can be used to interpret the tables and confirm 

 determinations. It must be remembered, however, that the venation 

 varies a little within specific limits, and of course still more within a 

 large genus. 



For the local species, the student will use the tables of Boulder County 

 bees, published in these Studies, Vol. IV, June, 1907. The artificial 

 key is mainly to genera, but species have been run in when convenient, 

 these being nearly all additions to the Boulder County list since June, 

 1907. Several genera, and some species, not at present known from 



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