Enallagma annexum
photo (above) 9 Sep 2006 Wagon Caves, Los Padres NF
Northern Bluet is a common and widespread bluet across much of North America. Its range was once thought to include northern Eurasia, but recent genetic studies (Turgeon et al. 2005) showed that Eurasian and North American populations separated about 250,000 years ago and should now be considered separate species. The Eurasian Bluet goes by the name Enallagma cyathigerum — which was the name given to the combined group (e.g., Manolis 2003) — but now that they are split, the North American bluet is Enallagma annexum. The photo below illustrates that an abdomen can be very flexible (all bluets can do contortions).
photo (above) 23 Sep 2006 upper San Antonio River, Los Padres NF
photo (below) of appendage: 9 Sep 2006 Wagon Caves, Los Padres NF
Male Northern Bluets show a lot of blue, and comparatively little black, on abdominal segments 2 through 5. This helps separate them from Arroyo and Tule Bluets. All male bluets are best identified by in-hand views of the terminal appendages. The male's lower appendages (paraprocts) are hooks that are much longer than the upper appendages (cerci; see photo right). The cerci themselves have a very tiny hook at the tip — almost too small to be seen in this photo but clearly visible with a 10X lens in-hand — that separates them from the otherwise very similar Boreal Bluet E. boreale. Northern and Boreal Bluets often occur together on lakes across much of North America, including California mountain ranges, and hybridization is known (McPeek 1990). However, the best interpretation of molecular data so far is that these are two reproductively isolated species (Turgeon et al. 2005).

Boreal Bluet has not yet been recorded in Monterey County but it is to be expected. It has been collected in adjacent San Benito County. Since it shares similar habitats with Northern Bluet, it might be found at the same spots. Boreal Bluet has a shorter flight season than Northern: just late April to early September, compared to Northern's mid-March into October (Manolis 2003).

Female Northern Bluets cannot be safely separated from female Boreal Bluets, even in-hand (Manolis 2003). Both species show blue atop segment 8, like shown on the photo (left). This photo was taken at over 7000' elevation in Alpine County, California. I think this photo is of a Northern Bluet because we only netted male Northerns at this lake, but it is still just a guess. I have not yet seen a female bluet of this type (Northern/Boreal) in MTY.

Photo (left) 15 Aug 2006 Heenan Lake, Alpine Co.

Northern Bluet is very common around high-altitude lakes in montane California (Manolis 2003). In Monterey County it has been found along streams, rivers, and seeps in the foothills of the Santa Lucia Mountains (map). It probably occurs on small montane lakes as well, but such lakes are very few in MTY. To date the elevational range in MTY has been 1600-3200' elevation (500-975m). 

Since it also occurs in Pinnacles National Monument — in the Diablo Range of San Benito County just east of MTY — it is probably widespread in habitat within MTY as well. However, it has not yet been found in the Diablo Range in MTY. 

MTY flight dates of Northern Bluet range from 23 Mar–23 Sep. Elsewhere in California it has been found mid-March to mid-October (Manolis 2003).

Literature cited:
  • Manolis, T. 2003. Dragonflies and Damselflies of California. Univ. of Calif. Press, Berkeley.
  • McPeek, M.A. 1990. Determination of species composition in the Enallagma damselfly assemblage of permanent lakes. Ecology 71: 83-98.
  • Turgeon, J., R. Stoks, R.A. Thum, J.M. Brown, and M.A. McPeek. 2005. Simultaneous Quaternary radiations of three damselfly clades across the Holarctic. Amer. Naturalist 165: E78-E107 [electronically published]
Web resources:
Major identification web sites with much information on California odes include: For sites with excellent photos to compare for identification or to simply enjoy, see: Many of these sites have links to other useful pages. Kathy Biggs's site is particularly useful in her selection of links.

All photos © Don Roberson 2007


Page created 1 Nov 2006