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 is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
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Feathers5
Posts: 287
Posts: 287
Feathers5 on Mar 14, 2013March 14th, 2013, 5:14 am EDT
I realize we post microscopic photos of bugs for identification purposes and that's a great practice. I'd like to make a request-suggestion that at least one photo of the specimen be photographed from a regular ocular distance.
Crepuscular on Mar 14, 2013March 14th, 2013, 5:56 am EDT
Are you talking about nymphs or adults and what species?
Feathers5
Posts: 287
Posts: 287
Feathers5 on Mar 14, 2013March 14th, 2013, 6:10 am EDT
Any species and stage of maturity. If you post a nymph for example, back off on the macro for just one shot of whatever you're photographing; nymphs, emergers adults, spinners, or the O'Jays.
Crepuscular on Mar 14, 2013March 14th, 2013, 6:43 am EDT
Here are a couple shots of a dun from when we were in Milesburg last week.
Lastchance on Mar 14, 2013March 14th, 2013, 5:59 pm EDT
Excellent! That's exactly what I mean. Thanks, Eric.
Is it my eyes or does thorax remain a lighter olive color?
The abdomen seems to have turned a dark olive/grey, but the thorax appears a lighter olive color.
Is it my eyes or does thorax remain a lighter olive color?
The abdomen seems to have turned a dark olive/grey, but the thorax appears a lighter olive color.
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