|Male Spotted Spreadwing, Lestes congener|
(close-ups of the photo at top): the head and
thorax above, the end of the abdomen below.
There is often times a very thin pale median stripe on the thorax too, but not always. There are one or two dark elongated spots—what this species is named for, low on each side of the thorax, and often visible from a lateral view (see the female below). Other species, at least sometimes, have these too, so don’t assume you’re looking at this species if you see spots.
If you can see them, the males’ paraprocts (lower abdominal appendages) are short—about half the length of the longer curved cerci (upper abdominal appendages). The Archilestes (California and Great Spreadwings) have short paraprocts too, but they are noticeably bigger species with unique thoracic patterns. Our other Lestes, however, all have longer paraprocts. As always, I encourage in-hand examination if you want to make sure.
Female Spotted Spreadwings are very similar to males in overall pattern and coloration, but have little pruinescence, especially on the abdomen. Their eyes are always brown unlike the females of our other species which are sometimes, at least, blue (the females of some species are polychromatic with either blue or brown eyes at maturity). The ovipositor is relatively short, but this can be difficult to judge without experience or comparison to other species. Some other species have short ovipositors too.
|Female Spotted Spreadwing, Lestes congener.|
The Black Spreadwing has a more robust build—females especially, and quite often has more obvious colored metallic green, purple, or bronze reflections on the thorax (sometimes abdomen too). The males’ paraprocts are longer with angled tips that are vaguely foot-shaped; the female’s ovipositor is a bit longer and more hefty.
Another difference is that male Black Spreadwings often, but not always, have more extensive pruinescence at the end of the abdomen, extending more noticeably onto S8. I’ve also noticed a little difference in the shape of the pale antehumeral (“shoulder”) stripe—at least on males: on Spotted it tends to be a little constricted before a more bulbous tip at the posterior end; on Black it is more evenly tapered. This is a subtle difference and subject to variation (like all characteristics). Again, I encourage in-hand examination of the structural differences if you want to be certain.
So look for the late-flying Spotted Spreadwing if you still have some decent weather in your area—I’m thinking the warmer parts of Northern California at this date. I don’t expect to see anything in my neck of the woods until next spring, but it will be much longer until the Spotted Spreadwings are out again!