Saturday, August 9, 2014

They're so hard to find: the "long-horned case-maker" (Leptoceridae), Nectopsyche exquisita

(Note: Entries from now on will normally focus on unusual, or new, insects and -- when I can get them -- good photos.)

I was so happy to see this this morning.  The Rivanna River at Darden Towe Park: a long-horned caddisfly (Leptoceridae), genus -- Nectopsyche; species -- exquisita; tolerance value, 4.3.  They make thin cases of sand which are attached to plant stems, the tough, green, vegetation that covers a lot of the rocks in the Rivanna in summer.  Finding one among all of the stems sticking up from those rocks is a matter of luck: I think I've compared it before to "looking for a needle in a haystack."

The "long-horned caddisfly" gets its name from the size of its antennae: they're exceptionally long.  That's true for the adult as well as the larva.  On most case-makers, the antennae are tough to see, even with a microscope view.  Not so with this one.

On the genus ID, Beaty has this to say: "Hind tibia not secondarily divided; middle leg with slender, slightly curved claw; circularly roughened lateral hump with posteriorly directed sclerotized bar which is apically curved towards the venter." ("The Trichoptera of North Carolina," p. 92)

For the "curved claw" and the "lateral hump" we need microscope shots.

But the lack of division in the hind tibia shows up very well in this live shot from this morning.

Also visible in this photo are two of the features used to establish the species ID: the mottled head and the dark bands at the joints on the legs.  Beaty: "N. exquisita - larvae up to 13 mm; metasternum with 8 setae; dorsum of head mottled with combination of light spots surrounded by dark pigmentation and dark spots on a light background; middle and hind legs completely dark or with dark banding at joints (but varies in some populations).  Case tubular and tapered, made mostly of sand with plant stems extending from anterior end.  Common and widespread." (p. 92)

The dorsum of the head also shows up very well in this photo.  That's the small minnow mayfly Heterocloeon curiosum (female), going along for the ride!

A wonderful find.  It's one of the insects I hope to see every summer.

I was also able to get some good shots of a fully intact flatheaded mayfly, Heptagenia marginalis.

This is the largest nymph that I saw -- but I saw a lot of them on the rocks.  The lime-colored spots on terga 1, 8, and 9 -- and the tapered shape of the body -- give them away.  A beautiful insect.


But this was the catch of the day.


  1. Thank you for deciding to continue to post - there are people out here in cyberland that pay attention to the things you post. I for one enjoy reading about the different nymphs you find and have learned more than I every could have than from books alone. Thanks!

    1. I'll probably post fewer entries. But, I just enjoy it too much to totally quit. Thanks for the comment. It's satisfying to know that what I'm doing is useful to others.