Late Season Bluets

Bluet sp.

I was intrigued by the small blue damselflies I saw lurking in the vegetation at the storm water ponds earlier on Sunday, so I returned later that afternoon with my net in order to catch them and identify them. The blue-type bluets are among the most difficult damselflies to identify, requiring a hand lens to see the male’s terminal appendages in order to distinguish between several similar-looking species. Fortunately there are fewer species flying this time of the year than in June and July, narrowing down the tricky possibilities to only a handful: Northern Bluet flies until mid-September, while both Familiar Bluet and Tule Bluet fly into October. Other blue-type bluets are already gone for the year, including Hagen’s Bluet (which flies until mid-August) and Marsh Bluet (which flies until early September).

I wasn’t surprised when I caught my first Familiar Bluet, a species I had photographed here before and identified with the help of some friends on the Northeast Odonata Facebook page.

Familiar Bluet

The Familiar Bluet has a pale tubercle at the tip of its cercus (the upper appendage) and a dark “arm” that extends above the tubercle. These structures showed up quite well in one close-up photo:

Familiar Bluet

The Familiar Bluet is one of the most common and widespread damselflies in North America. It breeds in a variety of still and slow-moving water habitats, including slow-flowing streams, marshes, vegetated lakes and ponds, and even river edges with emergent vegetation. Its range extends across the U.S. and into southern Canada from Newfoundland to BC. As it can tolerate different environmental conditions, including saline waters, it often quickly colonizes newly created wetlands. It is not surprising that this species moved into the reconstructed storm water ponds so soon after they refilled with water a couple of months ago.

I wasn’t expecting to find more than one species at the ponds, but when I caught a bluet whose appendages looked a little bit different I suspected I had a Tule Bluet, and once again the Northeast Odes group confirmed my suspicions.

Tule Bluet

The Tule Bluet is quite similar in appearance to the Familiar Bluet, though the Familiar Bluet is said to be paler and bluer in general – the Tule Bluet may look greenish compared to Familiar Bluet. From above, the black markings on the abdominal segments are longer than those of the Familiar Bluet, particularly in the middle segments. While the black markings look like thin rings on the Familiar Bluet, they extend to about one-half of each segment on the Tule Bluet. Of course, the abdominal pattern is variable among individuals, so this is not a reliable field mark for identification.

Once again a close-up view of the terminal appendages is required for identification. The male Tule Bluet also has a pale tubercle at the tip of its cercus, though it has dark arms both above and below the tubercle, which extends beyond the cercus itself. The tubercle of the Familiar Bluet does not extend beyond the cercus.

Tule Bluet

The Tule Bluet has a range that extends across the U.S., except in the southeast, and in southern Canada from Nova Scotia to BC. It, too, inhabits marshes, ponds, lakes, and open waste water ponds, though it doesn’t particularly matter if a wetland is well- or sparsely vegetated. This is the first time I can recall seeing one away from the Ottawa River.

Here are a few other bluets I photographed, though I wasn’t able to get a good, sharp image of the appendages on any of them. The deep blue colour, however, and the thin black rings in the middle of the abdominal segments make me think these are all Familiar Bluets. I suspect this species outnumbers the Tule Bluets at these ponds, as I was able to identify a few Familiar Bluets in the hand and only one Tule Bluet during my time there.

Bluet sp.

It was great to be able to finally put names to these small black and blue fellows. I can’t wait to return next summer and see what else may be flying in the newly reconstructed ponds – hopefully the Fragile Forktails and Rainbow Bluets I saw a few years before construction began are still there, and hopefully some new species will show up too!