AN INTRODUCTION TO THE STUDY OF THE 

 ANTS OF NORTHERN COLORADO 



By Wilfred W. Robbins 



The present paper is offered as a beginning in the study of Colorado 

 ants. Myrmecologists have collected and studied in the state, but the 

 results of their work are scattered. No systematic work has been done 

 upon the composition of our ant fauna, upon problems of distribution, 

 habits, etc. Professor William M. Wheeler is intending to publish soon 

 a list of the ants of Colorado, including all the material which he has 

 collected or received from different parts of the state. Such a list is 

 much needed and coming from the pen of Professor Wheeler will be 

 highly valuable and indispensable. 



The following enumeration of species occurring in northern Colorado 

 is necessarily incomplete, but it presents something upon which to build. 

 It is hoped that the artificial key will facilitate the labor of identification 

 of genera and enable those who are beginning the study to find their way 

 more easily. Keys for the separation of species are not available. 1 



Artificial Key to Genera of Ants Known to Occur in Northern Colorado 

 {For the identification of workers) 2 



I. Pedicel of abdomen one- jointed (fig. i). 



A. Abdomen proper constricted between segments i and 2 (fig. 2a). > Ponera 



B. Abdomen proper not constricted between segments 1 and 2. 



1. Antennae o-jointed; small red ants. Brachymyrmex 



2. Antennae 12-jointed. 



a. Large, slowly moving ants, usually black; frontal carinae sinuous, in form 

 of 5. Camponotus 



b. Not as above. 



a) Ocelli absent or indistinct. 



a) Basal prolongation of abdomen covering the pedicel (fig. 2e); small 

 black ants. Tapinoma 



b) Basal prolongation of abdomen not covering the pedicel (fig. 1). 



aa) Anal aperture circular (fig. $g); clypeus trapeziform; legs 

 short. Lasius 



bb) Anal aperture in form of transverse slit (fig. $h); clypeus tri- 

 angular; legs long. Iridomyrmex 



1 In his recently published book, Ants, Professor William M. Wheeler gives a key to the subfami- 

 lies, genera and subgenera of the North American Formicidae for the identification of workers. 



2 Wheeler has described a new inquiline genus Sympheidole based upon specimens from Boulder and 

 Colorado Springs. The description is based upon males and females, the workers being apparently non-existent. 

 The key in hand being based upon workers, the above genus is not included. 



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