Let’s consider Oregon and Washington as a single region and the ten clubtails which are found there collectively (see the graph below). Half of the species have started emerging by the end of May; June through August are the peak months with all ten species recorded in July; things are winding down by the latter half of August with six species recorded in September—and most of those are nowhere to be found by the middle of the month. But look at October and November, each with one species recorded. That’s the tail end of the Olive Clubtail season in this area.
|The number of clubtail species (Gomphidae) recorded as adults in Oregon and Washington per month. The lone species recorded in October and November is Olive Clubtail, Stylurus olivaceus. Sources: Johnson (2012) for Oregon; Paulson (2011) for Washington.|
What’s interesting is that the species was not even known to be on the lower Columbia River, or anywhere in Oregon for that matter until 1997 (Johnson, 1998), but I’m sure that was just a matter of no one checking its shores during the right time of year. It is the only gomphid you can expect to see on this part of the Columbia River and the adjacent reaches of its bigger tributaries.
|Male Olive Clubtail (Stylurus olivaceus) along the Columbia River in Vancouver, Washington.|
Emergence in this area starts in July, and the exuviae are not hard to find along the high water line where fine debris is deposited. Adults are quite common and easy to find during August and September, at least, and usually into October as long as the weather stays nice. I have twice found them in Vancouver during the month of November—in 1999 and again in 2010. That requires unusually pleasant conditions at that time of year.
|Male Olive Clubtail (Stylurus olivaceus). This shot shows off the male's club a bit better. This was taken in Vancouver, Washington, on 5 November 2010—the latest date for the species in the state thus far—during unseasonably summerish weather.|
|The male's club.|
Females are similar in appearance to males, although the pale coloration on the thorax is bit more yellowish, the abdomen has more extensive pale patterning, and their eyes are often not quite as vibrant. Her abdomen has just a tiny bit of expansion where the male’s club is located, and, of course, her abdominal appendages (cerci and epiproct) are far less substantial.
|Female Olive Clubtail (Stylurus olivaceus), Vancouver, Washington.|
|Pair of copulating Olive Clubtails (Stylurus olivaceus), Vancouver, Washington.|
|Male Olive Clubtail (Stylurus olivaceus), Humboldt River near Winnemucca, Nevada. Note the less extensive dark markings compared with other males shown here.|
Here are a few final close-ups of the lower Columbia River gomphid . . .
|Male Olive Clubtail (Stylurus olivaceus) feeding on a beetle, Vancouver, Washington.|
|Male Olive Clubtail (Stylurus olivaceus) doing some neck exercises, Vancouver, Washington. Note the gap between the eyes on top of the head— a characteristic of all gomphids.|
Johnson, J. 1998. Stylurus olivaceus in Washington and Oregon [PDF]. Argia 10(3): 20–22.
Johnson, J. 2012. Oregon Odonata Early/Late Flight Dates [PDF]. Accessed 03 Nov 2012.
Paulson, D. 2011. Washington Odonata [WWW page]. Accessed 03 Nov 2012.