Friday, January 7, 2011

Black Petaltail (Tanypteryx hageni), the Dragonfly of Soggy, Seepy, Slopes

One of my favorite odonates is the Black Petaltail, Tanypteryx hageni, and I presume it makes the top five on most Northwest odonatists’ lists for a number of reasons. It’s always a joy when I can see and handle these creatures, but especially so when I stumble across them unexpectedly during an outing.

This species’ family, Petaluridae, is a small one with only eleven species, nearly all of which are distributed around the Pacific Rim. Seven of these are found in Australia and New Zealand which seems unfair, and some of those are among the largest odonates in the world. The Petaluridae are known as petaltails because the males of most species have relatively broad, flat cerci (upper abdominal appendages) which are reminiscent of flower petals.

Male Black Petaltail (Tanypteryx hageni)
at Eight Dollar Mountain, Oregon.
The Black Petaltail is the sole western North American representative of the family, distributed from northern California (and barely into Nevada) to coastal mainland British Columbia (but strangely not on Vancouver Island) as this map at illustrates. The only other member of the genus is Tanypteryx pryeri of Japan. The more distant cousin Gray Petaltail, Tachopteryx thoreyi, occupies woodlands in a large swath of the eastern US from east Texas to New Hampshire.

Adult Black Petaltails are largely black, as the name suggests, with a complex pattern of yellow spots on the thorax and abdomen, a mostly yellow face, and dark chocolate brown eyes—and if you get a close look note that there is a gap between the eyes on top of the head (only the clubtails, Gomphidae, share this characteristic among the dragonflies). It’s a relatively large species among the Pacific Northwest odonates, although it is near the small end of the spectrum among the Petaluridae and it doesn’t quite reach the size of most of our darners (Aeshnidae). They are fairly approachable as dragonflies go and it’s not unusual for them to perch on people—especially those wearing very light-colored clothing, and this imparts upon them a warm and fuzzy “personality”.

Look for Black Petaltails in forested areas with open or partially open seepy slopes with a soggy substrate of mud, moss, and herbaceous plants, fed by springs or small streams. In Oregon and Washington these sites are mostly in the Cascade and Olympic Mountains above about 2000 feet elevation, but they also use Darlingtonia (a pitcher plant) fens in southwest Oregon, some of which are as low as 1000 feet elevation. There was once a population on Mary’s Peak—the highest point in the Oregon Coast Range, but they have not been seen there in decades and I’m not sure anyone alive knows where the site was anymore. In 2009 Mike Patterson found a population on Onion Peak, Clatsop County, which is currently the only known Oregon Coast Range population. There must be others.

A Black Petaltail (Tanypteryx hageni) nymph at its
burrow entrance after dark. Photo by Cary Kerst.
Being aquatic insects, the nymphs of the Black Petaltail live in the saturated substrate on those soggy slopes. And they don’t just crawl around in the muck—they actually construct burrows into the mud and organic matter and this is what makes the species really unique among the North American odonate fauna (and this is true of most members of the family). The nymphs are partially terrestrial after dark, sitting at their burrow entrance where the ground is wet, but above standing water (see Cary Kerst’s photo at right). Here they wait for prey to amble by, but they may also wander a bit to hunt.

The burrow entrance of a full grown nymph is about a half inch or a little more in diameter and there is often a small pile of excavated mud just off the threshold if it’s in use. They can be really difficult to spot, but it gets easier after you've seen a few. During the day you can sometimes see the occupant hanging back in the shadows of their burrow, and at times you can even fish them out with a blade of grass. If you do fish one out, be sure to return it to its home if you don’t intend to collect it. The nymphs take five years or so to get to full size—maybe a bit more at the highest sites, maybe a bit less at the lowest Darlingtonia sites. Of course once they emerge and become adults, they don’t live beyond the season.

Adult females lay eggs by inserting the end of their abdomen into the muck and mosses while grasping vegetation or clinging to the side of a log. They are difficult to see while they’re ovipositing, especially when surrounded by taller plants, but you often hear their wings vibrate or rattle against vegetation periodically and that can help you zero in on their location. Adults are often found soaking up the rays on logs, boulders, and tree trunks, and they don’t appear to wander very far from nymph habitat—at least not as much as other dragonflies. If you happen to come across one in the hills, there is probably a soggy slope in the area.
Female Black Petaltail (Tanypteryx hageni) at Todd Lake, Oregon.

A female Black Petaltail (Tanypteryx hageni) ovipositing in a Darlingtonia fen at Eight Dollar Mountain, Oregon.

So keep an eye out for the Black Petaltail when you’re in the hills on warm sunny summer days. It’s a special dragonfly in my opinion. And if you find some soggy slopes, look for the little burrows of the nymph and go fishing!


  1. Hi Jim -- Great article. Concise and well written and with nice pictures as well. This past summer, I found several new Black Petaltail locations here in the Southern Cascades. The closest is 9 miles east of my house. It's a very interesting animal.


    Ray Bruun
    Shingletown, CA

  2. @Ray Bruun Thanks so much, Ray. I'm testing out a new reply-to-comment button, so your comment is the guinea pig!

  3. Howdy Jim,

    This post is exciting to me because I came across a big, beautiful dragonfly in the Olympic Mountains a couple summers ago. I took some not-so-good photos, but looking at your photos here I can see that the beast was a Black Petaltail. And the habitat was just right: a sloping wet meadow at high elevation.

    Thanks for the great info!

  4. @Ivan Phillipsen

    Hey Ivan,

    I'm glad you enjoyed the post and found it useful. Thanks for the comment!

  5. One flew into my bedroom window tonight, biggest dragonfly i have ever seen scared me half to death was able to get my cat away from it long enough to capture it and set it free

  6. Hi Jim,

    Thanks for the great article. I just saw one of these the other day. I put a link to your article on my photo of it in my plant blog at I hope that's okay!

    1. Yes, of course! I'm glad you enjoyed the post.

  7. Thoroughly enjoying all the information and photography you have shared! Thank you!
    Found a female black petaltail on my hike on Mt. Ashland last week. Beautiful!