Bluets are a group of the damselflies that are often very difficult to identify to the species level, often requiring the capture of the insect and the use of a hand lens.
To further complicate identification, there are both Eurasian bluets (Coenagrion) as well as American bluets (Enallagma). Some other small damselflies, such as forktails (Ischnura), also resemble the bluets. Plus not all American bluets are blue; some are orange or green. The rainbow bluet is yellow, orange, and green!
In short, to learn more about these small (1.3") slender members of the Odonata, you'll want to have a good field guide and a keen sense of observation! But if you find a small blue damselfly flying weakly among the grasses it will likely be a bluet.
Watch for Behavior
Bluets stay in or near tall grass refuges because they are preyed upon by larger damselflies, dragonflies, other insects, and birds. To find bluets, walk slowly through tall grass near the edge of ponds or small lakes. Your movement will temporarily startle them into flying, usually only a few inches or feet, before they find another perch.
In good habitat, they will be very numerous and easy to find. Sometimes just sitting down in such habitat will permit you to watch several bluets at the same time.
Like all other members of the Odonata, they seek out flying insects on which to prey. Bluets have a weak, fluttery, short flights so are easy to follow on their short hunting forays.
Key ID Features: See narrative to the left. Typical male is shown above. Females, and some males, of other species within this genus may be orange, blue, or green.
Present in Park: June through September. Look in knee-high grasses surrounding a water feature.
Habitat: Ponds and small lakes.