Millcreek on Mar 23, 2015March 23rd, 2015, 3:57 pm EDT
These larvae are found in slack water and pools in Mill Creek (tributary to the Russian River). They begin to show around March and are pretty much gone by September. The cases change from small ones with redwood or Douglas fir needles to larger ones incorporating pieces of bark, small pieces of gravel and relatively large sticks.
"If we knew what it was we were doing, it would not be called research, would it?"
-Albert Einstein
Creno on Mar 23, 2015March 23rd, 2015, 6:09 pm EDT
looks like at least two species there - the one at the top has banded legs. There are lots of species that are quite difficult to separate. It is likely that many records have been mis-determined. Most species don't have adequately described larvae.
Millcreek on Mar 23, 2015March 23rd, 2015, 6:59 pm EDT
Yeah, the one at the top apparently is different. It would be interesting to
see if they change as they get older. Other than the banded legs they appear quite similar.
"If we knew what it was we were doing, it would not be called research, would it?"
-Albert Einstein
Creno on Mar 23, 2015March 23rd, 2015, 8:08 pm EDT
I don't think things like leg banding coloration will change. The color patterns should get more distinct with later instars. Most changes will occur with the addition/size of secondary setae/gills with later instars.
Millcreek on Mar 23, 2015March 23rd, 2015, 8:39 pm EDT
Interesting. I'm going to have to go back to my vials and see if I can find some with banded legs as later instars. Also see if other changes occur. I'll keep you posted.
"If we knew what it was we were doing, it would not be called research, would it?"
-Albert Einstein
Millcreek on Mar 24, 2015March 24th, 2015, 8:38 am EDT
I went back and looked through my vials. Found the original one with banded legs. It was the only one out of about 70 with banded legs. Either an aberration or another species. The others of that age range were quite close in appearance except for the legs.
"If we knew what it was we were doing, it would not be called research, would it?"
-Albert Einstein
Creno on Mar 25, 2015March 25th, 2015, 11:07 am EDT
The spacing humps of the 1st abdominal segment ("non-mammalian protrooberances" thought to be useful in respiration) are highly flexible, muscled, and, when viewed closely, have many small scales, setae, etc. They are retractile/extensile and, as such,the shape would be expected to be highly variable within both live and preserved material. I am not aware of the actual shape of the spacing humps having been used for taxonomic significance although their presence/absence, setation, scleritization, etc. is often used.