Montana Field Guide

The Prairie Bluet can be found anywhere in northern and eastern Montana except in the isolated mountains, it is most abundant in June at sun soaked prairie sloughs, marshes and slow streams. Like other Bluets, the Prairie Bluet is a vivid blue with dark markings. Females are less brightly colored. The small prairie bluet (30 mm or ~1in. long) has distinctive patterns that make it relatively easy to identify from other bluets. The blue rings on the abdomen become narrow towards the abdominal tip, which is bright blue. The bottom halves of the bulging eyes are green. A small black crescent shaped marking on the dorsal surface of the second abdominal segment should verify. Females are usually yellowish or greenish. Like all members of its family, the Prairie Bluet is a weak flier and rests horizontally with wings folded over the abdomen.

Adults are flying June through August

The small prairie bluet (30 mm or ~1in. long) has distinctive patterns that make it relatively easy to identify from other bluets. The blue rings on the abdomen become narrow towards the abdominal tip, which is bright blue. The bottom halves of the bulging eyes are green. A small black crescent shaped marking on the dorsal surface of the second abdominal segment should verify.

Prairie ponds, sloughs, and marshes as well as slow-flowing streams are the preferred habitats of the Prairie Bluet. Many of these open sunny wetlands can dry out during the summer months or freeze completely in winter (Westfall and May 1996, Acorn 2004, Paulson 2009).

Larvae feed on a wide variety of aquatic insects, such as mosquito larvae, other aquatic fly larvae, mayfly larvae, and freshwater shrimp. Adult- This damselfly will eat almost any soft-bodied flying insect including mosquitoes, flies, small moths, mayflies, and flying ants or termites.

Male Prairie Bluets tend to occur more commonly in the grasses along the shoreline, rather than out over open water. Copulation is prolonged and oviposition is usually in tandem with the pair submerging to deposit eggs on emergent plant stems (Paulson 2009).

Interestingly, the larvae halt their growth in the early winter and embed themselves into the ice of the stream or pond. The larvae themselves do not freeze, as their bodies produce a natural antifreeze in their blood which keeps them safe. In the spring, when the ice melts, the larvae continue their development (Acorn 2004, Paulson 2009).

The process where Prairie Bluet larvae freeze into stream or pond ice may a limiting factor to the geographic range of this species. This adaptation essentially makes Prairie Bluets solely dependent on habitats that do freeze solid such as those without much snow cover or in areas that are open and windy. These overwintering habitat requirements may be preventing them from expanding their range into more westerly or forested areas where significant snow cover insulates and thereby keeps water temperatures much warmer (Acorn 2004).