Hagen’s Bluet

02 / Field guide

Identification

Males are blue with black abdominal marks and are extremely close to Marsh Bluet; reliable separation often depends on terminal appendages.

The blue-and-black male closely matches Marsh Bluet in ordinary views; terminal appendage structure is the decisive field character. Females may not be safely separable from a casual photograph and should remain conservatively identified when structure is hidden.

03 / Field guide

Documented range

Hagen's Bluet ranges from British Columbia, the Northwest Territories, Manitoba and Quebec south to Colorado, Missouri and Maryland, continuing in the Appalachians to Georgia.

Colorado is the checklist's southwestern endpoint. It should not be presented as a general Arizona, California, New Mexico, Nevada, Texas or Utah species.

04 / Field guide

Habitat & flight period

Vegetated ponds, marshes and quiet lake edges, especially in cooler northern or upland settings.

Primarily a summer species at western mountain sites, with emergence after persistent water has warmed.

05 / Field guide

Finding strategy

Where Hagen’s and Marsh Bluets overlap, obtain close side and dorsal photographs of the male abdominal tip and avoid field identification from color pattern alone.

At cool, vegetated Colorado ponds and marshes, first determine whether Marsh Bluet also occurs. Work for a true lateral image of the abdominal tip, using manual focus confirmation if the wings attract autofocus.

06 / Field guide

Similar species

Marsh Bluet is the key lookalike. Females may be unidentifiable from ordinary field photographs and should sometimes remain at genus level.

07 / Field guide

Photography in the field

Prioritize a clean diagnostic view over magnification: terminal appendages must be sharp, unobscured and close to the focus plane.

Protect the water edge, keep a working distance, and leave the insect and its perch as found.