Hex Mayflies
Hexagenia limbata
The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
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This one seems to lead to Couplet 35 of the Key to Genera of Perlodidae Nymphs and the genus Isoperla, but I'm skeptical that's correct based on the general look. I need to get it under the microscope to review several choices in the key, and it'll probably end up a different Perlodidae.
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Caddisfly Species Hydropsyche californica (Spotted Sedges)
Hydropsyche californica together with Hydropsyche occidentalis (both commonly referred to as Spotted Sedge or Spotted Caddis) are the most important Hydropsychidae in the West. It can also be stated that they are arguably the most important western hatches of any kind, at least to the trout if not anglers. On freestone rivers and streams their numbers can be truly astounding. This is especially so on tailwaters.
Where & when
Distributed throughout the West, but their concentrations are highest in the West Coast states.
In 51 records from GBIF, adults of this species have mostly been collected during July (27%), August (22%), June (18%), September (10%), May (8%), and April (8%).
In 3 records from GBIF, this species has been collected at elevations of 4600, 6000, and 13671 ft.
Species Range
Specimens of the Caddisfly Species Hydropsyche californica
1 Larva
Size - 14 mm
Condition - preserved
Habitat - cobble bottom, moderate flow run, at a depth of approx. 1 1/2 feet.
Key Characters - pair of large prosternal sclerites
This is a very common taxon at this location. I collected using a kick net. In life, it is bright olive green ventrally, shading to a dull olive at its dorsal abdominal surfaces. In the hand, the legs, thoraxic regions, and head appear medium chocolate brown. The stark contrast of the thoraxic plate's dark edges and light legs are effects of preserving. The plumouse anal hooks were duck down gray, not the color of the gills as appears in the preserved specimen.
The Lower Yuba River is a good habitat for this species, being a larger river with an open canopy. The Feather River just to the north of the Yuba system also finds H. californica in abundance. The other common Hydropsyche species in the area, Hydropsyche occidentalis, seems to prefer smaller, shaded streams.
Entoman
Condition - preserved
Habitat - cobble bottom, moderate flow run, at a depth of approx. 1 1/2 feet.
Key Characters - pair of large prosternal sclerites
This is a very common taxon at this location. I collected using a kick net. In life, it is bright olive green ventrally, shading to a dull olive at its dorsal abdominal surfaces. In the hand, the legs, thoraxic regions, and head appear medium chocolate brown. The stark contrast of the thoraxic plate's dark edges and light legs are effects of preserving. The plumouse anal hooks were duck down gray, not the color of the gills as appears in the preserved specimen.
The Lower Yuba River is a good habitat for this species, being a larger river with an open canopy. The Feather River just to the north of the Yuba system also finds H. californica in abundance. The other common Hydropsyche species in the area, Hydropsyche occidentalis, seems to prefer smaller, shaded streams.
Entoman
Start a Discussion of Hydropsyche californica
References
- LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.
Caddisfly Species Hydropsyche californica (Spotted Sedges)
Species Range
Common Name
Resources
- NatureServe
- Integrated Taxonomic Information System
- Global Biodiversity Information Facility
- Described by Banks (1899)