Discovery on Vaal

[Nymph+O-]

Yes ladies & gents , fellow inmates and entomology nerdOMR
Yet another awesome discovery on the Vaal. Found these Pale Burrowers (Polymitarcyidae). This specific specimen in the pic measured 30mm! I saw a couple of pupa shrugs drifting down stream - did not get a glimpse of any adults though. This has been the 4th awesome discovery on this specific piece of water amongst which were Stoneflies, Aquatic Caterpillars and Flat-Head Mayflies

P.S Check the jaws on that mother****er!

[Gerrit Viljoen]

Nice find Ferdie,

Cream,tan,pale yellow with a touch of brown is the way to go it seems.

G

[Nymph+O-]

Nice find Ferdie,

Cream,tan,pale yellow with a touch of brown is the way to go it seems.

G

Yeah, the colour is Cream to a pale brown. What makes this find so awesome is that it is on the list of very sensitive aquatic insect life - thus the water is in good quality. My size 6 control caddis looked like a baby burrower next to this puppy.

[chris williams]

Hi Nympho, good find! This would be a great find as these guys are usually found only in cleanish tropical and sub-tropical rivers. I can't quite make out much detail as the pic's a bit small and I can't enlarge it (story of my life..). Any chance you could resend it as a 'big photo' not a thumbnail? You know I'm only an ento-nerd not a computer one as well!!!

LOL
OMR

[Korrie]

they almost look like the Cracker/Snapper prawns you get in the estuaries.

[Nymph+O-]

i asume this is above the barrage. it would be flat out phenominal if we had SIGNIFICANT hex populations below the barrage.(i think whenever the flow goes high those hex's would get scowered rigth out their burrows). imagine a solid "drake" hatch on the vaal - that would be as good as flyfishing gets. i'm absolutely thrilled to see such big hex nymphs in SA.

below the barrage i've also found a number of aquatic catepillars which also indicate very good water quality. they are not worth immitating.

Agreed, I would not even try imitate those burrowers as there are far more other abundant food forms available to feed on. Just nice to discover those insects one read about in books on the Vaal.

Hi Nympho, good find! This would be a great find as these guys are usually found only in cleanish tropical and sub-tropical rivers. I can't quite make out much detail as the pic's a bit small and I can't enlarge it (story of my life..). Any chance you could resend it as a 'big photo' not a thumbnail? You know I'm only an ento-nerd not a computer one as well!!!

LOL
OMR

Pics were e-mailed Sir.

[chris williams]

Thanks, kind young man, well-received, I will get out my binoculars and report back before I get whisked off to the old age home for morning tea!!!

[Niel Myburgh]

Hi, what is that? I got the name above, but what fly would immitate them. A dragonfly?

[chris williams]

Ferdi,

Thanks for the e-mail with the bigger photos. That other specimen was especially nasty!!!

Yes, congrats, you are spot-on! This is indeed one of the Polymitarcyidae (yes, I had to look up the spelling as well since Latin is neither of our home languages...). I think you probably identified it from the useful 'Aquatic Invertebrates Of SA Rivers' by Gerber and Gabriel, which I know you've got?

Just for the guys that havn't, this book describes these mayfly nymphs as follows and I hope the authors don't object with my paraphrasing and adding further to your useful info:

Common name: pale burrowers
Very prominent mouthparts. Legs are adapted for digging into riverbanks. Long wavy gills on both sides of the abdomen. Sits quietly inside a burrow (rather like you, Nympho!). Active waving of the gills when at rest (unlike you, Nympho!). Muddy riverbanks, moderately fast flowing streams. Cream or pale brown. As the sensitivity scale goes, it likes water 10 out of 15 (15 being the purest). The one in the photo in the book is only about a centimetre long, but I've seen them much bigger than that around the Middle/Low Veld rivers/streams.

++

My comments:

I guess also you'd have found these above the Barrage as the water's generally cleaner there? It's most unusual to find these guys in the Vaal, as I mentioned before, they're generally tropical/sub-tropical. Maybe it's yet another sign of global warming? With the Vaal at, what, 21/22 deg C on average at present depending where you are, this may well be possible.

They are generally large nymphs as you've observed, with fringed side-gills and three short tails.

They do burrow in mud, also using the forward 'tusks' and strong legs to get them into silt, rotten logs and papyrus stems. Must be a bloody magic fun-filled existence. The gills they have towards the rear then start fanning to give them more oxygen when they're burrowed, which also helps them filter-feed the plankton and other mini-moogies. The adults, which I've occasionally seen hatching in summer evenings on the Lower Komati (but never - to date - Op-Die-Vaal, which should prove interesting!). The adults, without getting technical, have two sets of heavily-veined wings, two tails male, three tails female. The abdomen is grayish-tan on top and cream underneath. The thorax is an orangy-tan and they have black eyes, and very short legs.

As to imitating the nymph. Just an idea as I've never actually specifically imitated any, you could do a simple bleached pheasant tail nymph with the emphasis on a larger hind part with the side-gills, and a Koki'ed tan head. Or you could get really technical. I guess you'd fish this dead-drift as the nymphs aren't designed for Olympic swimming like the Baetidae ('small monniwflies'). I think I'll try and tie a few imitative prototypes - it's always good to have something new to try and concoct that fools more than merely myself!

All Hail to Nympho and the Pale Burrower - the Vaal's entomological answer to Prof. JLB Smith and the Coelacanth!!

Cheers
OMR

[Nymph+O-]

Ferdi,

Thanks for the e-mail with the bigger photos. That other specimen was especially nasty!!!

Yes, congrats, you are spot-on! This is indeed one of the Polymitarcyidae (yes, I had to look up the spelling as well since Latin is neither of our home languages...). I think you probably identified it from the useful 'Aquatic Invertebrates Of SA Rivers' by Gerber and Gabriel, which I know you've got?

Just for the guys that havn't, this book describes these mayfly nymphs as follows and I hope the authors don't object with my paraphrasing and adding further to your useful info:

Common name: pale burrowers
Very prominent mouthparts. Legs are adapted for digging into riverbanks. Long wavy gills on both sides of the abdomen. Sits quietly inside a burrow (rather like you, Nympho!). Active waving of the gills when at rest (unlike you, Nympho!). Muddy riverbanks, moderately fast flowing streams. Cream or pale brown. As the sensitivity scale goes, it likes water 10 out of 15 (15 being the purest). The one in the photo in the book is only about a centimetre long, but I've seen them much bigger than that around the Middle/Low Veld rivers/streams.

++

My comments:

I guess also you'd have found these above the Barrage as the water's generally cleaner there? It's most unusual to find these guys in the Vaal, as I mentioned before, they're generally tropical/sub-tropical. Maybe it's yet another sign of global warming? With the Vaal at, what, 21/22 deg C on average at present depending where you are, this may well be possible.

They are generally large nymphs as you've observed, with fringed side-gills and three short tails.

They do burrow in mud, also using the forward 'tusks' and strong legs to get them into silt, rotten logs and papyrus stems. Must be a bloody magic fun-filled existence. The gills they have towards the rear then start fanning to give them more oxygen when they're burrowed, which also helps them filter-feed the plankton and other mini-moogies. The adults, which I've occasionally seen hatching in summer evenings on the Lower Komati (but never - to date - Op-Die-Vaal, which should prove interesting!). The adults, without getting technical, have two sets of heavily-veined wings, two tails male, three tails female. The abdomen is grayish-tan on top and cream underneath. The thorax is an orangy-tan and they have black eyes, and very short legs.

As to imitating the nymph. Just an idea as I've never actually specifically imitated any, you could do a simple bleached pheasant tail nymph with the emphasis on a larger hind part with the side-gills, and a Koki'ed tan head. Or you could get really technical. I guess you'd fish this dead-drift as the nymphs aren't designed for Olympic swimming like the Baetidae ('small monniwflies'). I think I'll try and tie a few imitative prototypes - it's always good to have something new to try and concoct that fools more than merely myself!

All Hail to Nympho and the Pale Burrower - the Vaal's entomological answer to Prof. JLB Smith and the Coelacanth!!

Cheers
OMR

Wow! Well thank YOU, Sir - always a very informative, yet humouristic approach to the valuable information and experiences you share..... like I'd a keg of the goodness with a stranger.