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3. A couple of Odontoceridae - Marilia and Nerophilus

Admittedly it's a bit dubious whether these are of much importance for trout fishing but they are indicators of good water quality. Marilia pupae and adults can be numerous enough locally to create a good emergence.

Marilia is represented by one species in California, Marilia flexuosa. In this area of the Russian River its commonly collected in samples. The larvae spend most if not all of their time burrowed into the substrate. They are most commonly collected in riffles and glides with a fast flow of water and an unembedded substrate of gravel and cobble with deposits of fine to coarse sand and fine gravel. Larvae are almost never collected on top of the substrate but can be found in large numbers by digging in sand and gravel with your fingers. Pupae can be found on the sides and occasionally on the bottom of large pieces of gravel or cobble. They seem to prefer cracks or crevices on the rocks to attach their cases and are often found in aggregations. The larvae attach the case to the rock at the front and back, then use a small stone to plug each end of the case. Some larvae attach several stones to the posterior end of the case when preparing the pupal chamber. When pupae are ready to emerge they cut loose the rock at the front of the case. Marilia seem to prefer the mainstem of the river and I haven't found any in smaller tributaries.

Nerophilus is a monotypic genus represented only by Nerophilus californicus. Nerophilus larvae in this area are found in the smaller tributaries of the Russian River. They are usually collected in well canopied areas with a substrate of large cobbles and boulders with deposits of sand on the downstream side of them and a fast flow of water. All I have collected were found under the sand. I haven't found any pupae and collections of adults have been few and far between.

Wow! What great pics Mark...What little craftsmen they are.It is really cool to see how the antenna and legs are "stowed" in that tight space.

Thanks again!

Spence

Spence,


Yeah, these guys are really master masons. Nothing extra in the cases, but what's used is used to maximum effect. An excellent example of less is more.

Mark

Cool photos Mark. I get some pretty neat Odontocerids here from spring seeps that make their cases out of pieces of quartz. I think there is a post on here somewhere. Psilotreta rufa I found it...

http://www.troutnut.com/topic/7815/Another-Caddisfly#35252

Eric - Took a look at your link to the Psilotreta rufa photos. Interesting little critter. Also interesting that you found them out in the open. I haven't found Marilia larvae outside the substrate except for an occasional straggler. The pupae are out in the open on large gravel and cobble. Nerophilus larvae I've collected have always been under the substrate. I suppose they might come out at night but don't really know for sure.

On your post on Psilotreta rufa it seemed the larvae were variable in coloration. This is true of the Marilia larvae as well. They can vary from a cream to light green body color. Seems to be true of all the larval instars. Nerophilus larvae don't seem to vary much in color.

You might be interested in this site http://aquaticinsectsofcentralvirginia.blogspot.com/2011/09/found-odontoceridae-strong-case-maker.html if you haven't already run across it.