Arrow Clubtail Stylurus spiniceps

In September three species of Stylurus Clubtails, or Hanging Clubtails, gather at a small riffle on Seneca Creek, just above River Road, Montgomery Co MD, to mate and lay eggs. This is a half mile from the Potomac River, where large numbers of Stylurus clubtails emerge in June and July. Curiously, none ever emerge from the creek itself. The eggs or young larvae must float down to the Potomac, where they spend one or more years before emerging as adults. What the young adults do before breeding is also a mystery.

At the breeding site the clubtails are generally difficult to see. They spend nearly all of their time high in the trees. Occasionally a female drops down to make a ten second egg-laying run, or a few males chase each other about for a minute, before returning to the trees. Activity is greatest in late afternoon, and males at least may hang on low vegetation. Sun and 70 degree temperature are essential.

The flight shots are terrible, giving an idea of how hard it is to identify them with binoculars.

Arrow Clubtail Stylurus spiniceps Emerges in huge numbers. The largest and darkest of the three, with the smallest yellow spots, usually appearing separated, on segments 8 and 9.

Arrow Clubtails

Mating 50 feet up in a tree overhanging the creek. Video grab though the telescope at about 1000x

Laura's Clubtail Stylurus laurae Emerges in small numbers. Slightly smaller than Arrow, with fainter dashes down the abdomen, but very large, fused yellow spots on segments 8 and 9. Very hard to tell in flight.

Laura's Clubtails

Russet-tipped Clubtail Stylurus plagiatus Emerges in small numbers from the Potomac. Easy to tell by the pumpkin orange terminal segments. They really glow in flight.

Russet-tipped Clubtails

at left, through the telescope



OTHER SPECIES: Riverine Clubtail, Stylurus amnicola, was found at this spot about 40 years ago, not since. Elusive Clubtail, Stylurus notatus, was found upstream on the Potomac about 25 years ago. Exuvia recently found downstream. It may prefer to stay on the larger Potomac.