Mayfly Species Drunella lata (Large Blue-Winged Olive)
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)
» Species lata (Large Blue-Winged Olive)
Common Names
Recent taxonomic changes have served this species well, because several other popular species (Drunella cornuta, Drunella cornutella, and Drunella longicornis) are now recognized as synonyms (Synonym: A former name of a taxon, usually a species. Entomologists frequently discover that two insects originally described as different species are one in the same, and they drop one of the names. The dropped name is said to be a synonym of the remaining name. These changes take a while to trickle into the common knowledge of anglers; for example, Baetis vagans is now a synonym of Baetis tricaudatus.) of Drunella lata. The combined lata hatch now lasts for months.
Angling entomology books show several differences in hatching behavior between the former species now combined with lata. I've tried to parse these into a coherent picture here based on the geography of the old species, but I recommend consulting experienced local anglers to understand which of the many variations on lata behavior is prevalent in your area.
Where & When
For the most part, Drunella lata hatches much earlier in the East than in the Midwest.In the Catskills it runs from mid-May to mid-June, peaking in the last week of May. It comes a couple weeks later in the Adirondacks, which are on the Eastern schedule. The Midwestern emergence runs from late June through mid-August and peaks in late July.
A couple rivers in New York State are reported to have some lata hatches through late August, following the Midwestern timetable, but this is not common. Likewise, there are some hatches in the Midwest which follow the Eastern dates, from late May through early July, but they are relatively unimportant.
One of the less common lata varieties is reported to hatch from late June through late July in the mountain streams of southern Appalachia, where they emerge around noon.
Hatching Behavior
Time Of Day (?): Usually mid-morning, but flexible based on weather
Habitat: Some hatch in their usual fast-water habitat, while others move to nearby calm water.
Water Temperature: 50-60°F
Drunella lata emergence is generally spread out over several mid-morning hours in the Midwest, but the Eastern variety emerges mostly within an hour and a half. Their style of emergence is described on the Drunella page, and a couple authors note that trout prefer emergers over either duns or nymphs during this hatch. It is unclear whether they're referring to surface-film emerger patterns or wet flies to imitate the subsurface duns.Habitat: Some hatch in their usual fast-water habitat, while others move to nearby calm water.
Water Temperature: 50-60°F
The fresh duns undergo the immediate color changes detailed on the Drunella genus page. In this species, according to Hatches II, the color changes from a "pale greenish yellow" to a "medium olive" and eventually to a "dark dirty olive."
There is a curious mention of summer evening lata hatches by the Leonards in Mayflies of Michigan Trout Streams. It is likely they were talking about the spinners, but they were rigorous observers and it is not like them to make such a mistake.
Spinner Behavior
Time Of Day: Twilight
Habitat: Riffles
The lata spinner falls in the Midwest last about an hour around dusk, and they provide outstanding fishing. Caucci and Nastasi note in Hatches II that the trout may feed on the ovipositing females with aggressive slashes and that a hackled spinner pattern can be twitched to imitate the active egg-layers.Habitat: Riffles
The spinner falls seem to be unimportant in the East, where the females drop their eggs from high above the water.
Nymph Biology
Current Speed: Fast riffle water has the best populations, but some are found in slow pools and runs.
Substrate: Rocks of all sizes, gravel to cobble
These are among the most common nymphs in my samples on many Eastern streams in early June.Substrate: Rocks of all sizes, gravel to cobble
Drunella lata Fly Fishing Tips
The former division of lata into so many species reflects wide variation in both size and color of all stages. Studying specimens from your own waters is important.6 Mayfly Specimens in the Species Drunella lata:
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
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 Spinner
View 6 Pictures
View 6 PicturesRegion: Poconos
Collected May 27, 2007
Added Jun 4, 2007
3 Streamside Pictures of Drunella lata Mayflies:
View Full Size
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 lata
Midwest Lata Emergence 20 Replies »
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.
New features!
