Butterflies of the Colorado Front Range

Photographs, Species Accounts and Checklists

WELCOME to this accessible reference and general guide to the butterflies along the Colorado Front Range. This website was created by Catherine Cook, Donn Cook, and Joe Krieg, longtime volunteer naturalists with Boulder County Parks and Open Space. Drawing on decades of field experience and the expertise of many generous mentors, researchers, photographers, and butterfly enthusiasts, we developed this site as a resource for anyone interested in the butterflies of the Colorado Front Range. We are deeply grateful to everyone who has shared their knowledge, observations, and photographs to make this website possible.

The Colorado Front Range is defined as the area from the Colorado-Wyoming border south to Pueblo, from the Continental Divide to the plains, including the following counties: Larimer, Boulder, Broomfield, Gilpin, Clear Creek, Jefferson, Denver, Douglas, Park, Teller, El Paso, Fremont, and Pueblo.  This area encompasses five life zones: plains, foothills, montane, subalpine, and alpine. 

You will find butterflies listed in general taxonomic order by family, genus, and species.  Each species page includes photos taken in the field, a description of the butterfly’s appearance, wingspan, habitat, host plant(s), and life cycle, including adult flight time(s), and some extra information.  The adult flight time listed for each species is the most likely time for adults to fly along the Front Range, but flight times can fluctuate due to weather conditions, host plant availability, and/or north-south position along the Front Range region. There is also information on butterfly anatomy, conservation, a glossary of terms, and additional resources.

We hope you enjoy learning about the Butterflies of the Colorado Front Range!

Boulder County Nature Association (BCNA) is the host and sponsor of this website.

BUTTERFLIES IN BOULDER COUNTY

Butterfly Surveys have been completed on some Boulder County Open Space properties from 2002 to 2024 by Janet R. Chu and her butterfly research team.  Boulder County Parks and Open Space (BCPOS) and Boulder County Nature Association (BCNA) have encouraged and partially funded these important surveys with the resulting reports and analyses of trends. BCNA funded the 2007 continuation of a research program to survey Boulder County butterflies and the preparation of a 74-page report. The BCPOS Small Grants Program supported the surveys in 2004-2006.  Since then, monitoring of butterflies on Boulder County Open Space properties has been partially funded by the BCPOS and the BCNA Small Grants Programs. Links to later reports (PDF) on the Boulder County website are listed below.  

• Butterfly Research in Boulder County 2004 - 2007
• Butterflies A Continuing Study of Species and Populations In Boulder County Open Space Properties - 2011 Inventory and 2007-2011 Analyses
• Summary report of butterfly observations on the Anne U. White Trail in Boulder County before the September 2013 flood
• Additional Boulder County butterfly survey reports for the following years are published on the Boulder County website. (2002; 2003; 2004; 2005; 2006; 2008; 2009; 2010; 2011; 2013; 2018).

Butterfly Counts have been held at the Cal-Wood Education Center every July 4 for 41 years, 1984-2025. Cal-Wood is a registered nonprofit that connects children and adults to the Colorado mountains through environmental education, service, and recreation and is located near Jamestown, Colorado. A 29-page report on the Cal-Wood butterfly counts covering 1984 to 2014 is available as a PDF (3.8 MB).

• Cal-Wood Fourth of July Butterfly Counts, 1984-2014 

The field guides, Butterflies of the Colorado Front Range, 1^st and 2^nd editions, by Janet R. Chu and Stephen R. Jones, stem from research partially supported by the Boulder County Nature Association.