Mayfly Genus Drunella (Blue-Winged Olives)
Taxonomic Navigation -?-
Kingdom Animalia (Animals)
» Phylum Arthropoda (Arthropods)
» Class Insecta (Insects)
» Order Ephemeroptera (Mayflies)
» Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)
» Genus Drunella (Blue-Winged Olives)
2 species aren't included.
Common Name
| Match | Common Name |
 | Blue-Winged Olives |
Hatching Behavior
Drunella nymphs may emerge in the surface film, but more often they do it somewhere in the top 12 inches of water and then float the rest of the way as duns. They arrive on the surface soggy and ride its currents for a long time before their wings are dry enough for flight. Caucci and Nastasi in Hatches II note that they ride low in the water and are ideally imitated by the Compara-dun.All important species in this genus are said to change color dramatically as soon as they hit the air, and it's important to imitate the bright greens the trout see in the "fresh" duns rather than the muted shades of olive or ruddy brown that we find when we collect the duns later.
Nymph Biology
The nymphs are noteworthy for their identifying characteristic: the serrated appearance of their fore femora (Femur: The main segment of an insect's leg close to the body, in between the tibia and the trochanter.). They are also more flat and clinger-like than other "crawler" mayfly genera.
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8 Mayfly Specimens in the Genus Drunella:
Drunella tuberculata Mayfly Dun
View 14 PicturesI don't know for sure that this is Drunalla tuberculata, but that's my best guess for now.
It certainly has a different look and much more robust body shape from Drunella lata duns I photographed a couple weeks earlier, so I doubt it's that species. Using distribution records to eliminate other choices narrows this down to Drunella tuberculata or Drunella walkeri.
Markings described for the abdominal sternites (Sternite: The bottom (ventral) part of a single segment on an insect's abdomen.) of the male spinner of Drunella tuberculata are suspiciously similar to those on this female dun. Also, this dun is 9.5mm long (my ruler pic isn't very good, but I'm basing this on measuring the real thing). The size range given in the old Allen & Edmunds keys for walkeri females is 7-8mm, while tuberculata is 9-11mm. For these reasons I'm sticking it in tuberculata for now.
This is the only Drunella mayfly I saw all day. I scooped it off the water as it emerged at around 7pm from a big Catskill tailwater.
View 14 PicturesI don't know for sure that this is Drunalla tuberculata, but that's my best guess for now. It certainly has a different look and much more robust body shape from Drunella lata duns I photographed a couple weeks earlier, so I doubt it's that species. Using distribution records to eliminate other choices narrows this down to Drunella tuberculata or Drunella walkeri.
Markings described for the abdominal sternites (Sternite: The bottom (ventral) part of a single segment on an insect's abdomen.) of the male spinner of Drunella tuberculata are suspiciously similar to those on this female dun. Also, this dun is 9.5mm long (my ruler pic isn't very good, but I'm basing this on measuring the real thing). The size range given in the old Allen & Edmunds keys for walkeri females is 7-8mm, while tuberculata is 9-11mm. For these reasons I'm sticking it in tuberculata for now.
This is the only Drunella mayfly I saw all day. I scooped it off the water as it emerged at around 7pm from a big Catskill tailwater.
Region: Catskills
Collected Jun 1, 2007
Added Jun 8, 2007
Drunella lata (Large Blue-Winged Olive) Mayfly Nymph
View 7 Pictures
View 7 PicturesRegion: Upper Midwest
Collected Jun 5, 2005
Added May 25, 2006
Drunella lata (Large Blue-Winged Olive) Mayfly Dun
View 12 PicturesThis dun belongs to the lata variety formerly known as cornuta.
View 12 PicturesThis dun belongs to the lata variety formerly known as cornuta.Region: Poconos
Collected May 29, 2007
Added Jun 4, 2007
3 Streamside Pictures of Drunella Mayflies:
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A freshly emerged female Drunella lata dun.
In this picture: Mayfly Species Drunella lata (Large Blue-Winged Olive).
In this picture: Mayfly Species Drunella lata (Large Blue-Winged Olive).
Here's the bottom of a freshly emerged male Drunella lata dun, showing a lighter shade of olive than the specimens I photographed with my better camera in the evening.
In this picture: Mayfly Species Drunella lata (Large Blue-Winged Olive).
In this picture: Mayfly Species Drunella lata (Large Blue-Winged Olive).
Recent Discussions of Drunella
Midwest Lata Emergence 20 Replies »
Posted by DarkDun on Mar 4, 2007 in the species Drunella lata
Last reply on May 2, 2007 by Taxon
The D.Lata emerges in Michigan waters at 10 AM on the dot and stops at noon from about June 25 thru July 10. I have fished this hatch avidly for years and find it very punctual on moderately overcast days. Sunny days make it much shorter duration, about 30 minutes. A size 14 imitates it perfectly with dark dun wings, bright olive green body and med dun tails and legs at emergence. The body color does change to dark green after a while.
The D.Lata also is significant in PA Northern Streams in Mid May.
I have not encountered it in the South Appallacian streams as yet. I fish some smaller BWO (#16-20) in NC but none so large as D. Lata.
ReplyThe D.Lata also is significant in PA Northern Streams in Mid May.
I have not encountered it in the South Appallacian streams as yet. I fish some smaller BWO (#16-20) in NC but none so large as D. Lata.
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