Northern bluets are probably the most widespread and abundant aquatic damselflies. They are found in northern latitudes around the world. In North America these bluets are seen from Alaska to the Hudson Bay south to approximately Virginia and throughout California. Originally all northern bluets were classified as Enallagma cyanthigerum. In approximately 2005, genetic studies demonstrated that the Eurasian and North American northern bluets separated about 250,000 years ago and that they are two different genetic species. The North American northern bluets were given the scientific name Enallagma annexum and the Eurasian species retained the E. cyanthigerum appellation. The older literature and most field guides still do not make the distinction between the two species of northern bluets. Confusing, yes! DNA analysis is clarifying many classification questions, and at the same time creating other difficulties.
No matter what its scientific name, the northern bluet is a beautiful insect that belongs to the group of damselflies known as pond damsels. The male northern bluet is mostly blue on the upper side of the thorax with a conspicuous black stripe on the top of the thorax and thinner black stripes on the shoulders. The flexible abdomen is also mostly blue with black stripes. Northern bluets resemble blue jewels as they flit among the vegetation. Like most other damselflies, northern bluets hold their wings together when perched. The eyes are set far apart and have a “hammerhead” look. Females are olive green to brown or a much duller blue and have more black on the upper side of their abdomens. (Most of the time dragonflies can be easily distinguished from damselflies in the field because dragonflies hold their wings open and flat when perched and their eyes are close together.)
Northern bluets are found around lakes, ponds, marshes or slow-moving streams in a wide variety of habitats, from the sagebrush desert to mountain lakes.
The damselfly life cycle consists of egg, larval (also called nymph) and adult stages. While in the larval stage, damselflies go through several molts (or instars) before emerging as adults. Larvae eat aquatic insects. The adult northern bluet’s diet consists of small insects from plants, such as aphids, and soft-bodied flying insects including flies, mayflies, mosquitoes, and small moths. After mating northern bluets will begin to lay their eggs on aquatic vegetation then will move to the water and oviposit eggs below the surface. When the female northern bluet moves to the water to lay eggs she will go below the surface. The male guards the female while she is under the water and then helps her get back out of the water.
These northern bluets were photographed at Manzanita Lake in Lassen National Park (CA).