Sunday, September 25, 2011

The "Case-makers": An Annual Wrap-up

I've found some beautiful case-maker caddis this year, and it's a good time to review what we have seen, when we have seen them, and where.  I'll pretty much move through these in chronological order.

1. Uenoidae, common name "Uenoid".  Genus Neophylax.
The caddisfly in the picture at the top of the page is a "Uenoid" caddis, found on February 18th in Elk Run, a tributary of Buck Mt. Creek.  I started finding Uenoids on December 11th and continued to find them through April (even May, I think, in some small, mountain streams).  I think of the Uenoid as a "winter" case-maker since that's normally when we find them, and in some streams they are numerous and cover the rocks.   We find them in streams of all sizes -- though I've never seen them in "big" rivers like the Rivanna.  The cases are tube-like, usually slightly tapered, and normally have three large pebbles on each side, perhaps used for ballast -- though agreement on that is not universal.  Another photo below, pointing out the large pebbles on the sides.

2. Glossosomatidae, common name "Saddle case-maker."  Genus Glossosoma.
This is not a real case-maker according to Wiggins (see his Caddisflies: The Underwater Architects, pp. 20-28).   Unlike true case-makers it does not, for example, keep the same case throughout its life as a larva.  When it gets too big for its case, it abandons the case and makes a new one that's more "fitting" (Sorry. Couldn't resist!)  This is another caddisfly that I think of as a "winter" case-maker.  Again, I saw some on 12/11/10.  I found them on occasion through the winter months, but I also found some in June -- and even in August!  Still, we're most likely to see them in the winter months -- December through March.  The "saddle" case resembles the shell of a tortoise.  Normally, you won't see the larva until you turn the "shell" over (though sometimes they "peek" out from underneath, as in the first photo below).  Below, photos of the dorsal and ventral views, then one with the larva crawling out of its overturned shell.

3. Lepidostomatidae, common name "Lepidostomatid".  Genus Lepidostoma
Another "winter" case making caddis -- though in one small tributary to the Moormans, I did find one in June.  Most of the Lepidos I found, I found in January, February and March.  They commonly make a case that is 4-sided, skillfully crafted out of square pieces of bark.  Some of these are gorgeous when seen with magnification.  This, too, is primarily a small stream insect: look for them in forested, headwaters streams.  But, for whatever reason, we have found them in the Rivanna at Milton.  Below, three examples.

4. Brachycentridae, common name "humpless case-maker".  Genus Brachycentrus.
I'm not sure how to give these a date.  Ames (Caddisflies, p. 175) identifies this -- in fly fishing terms -- as the "American Grannom," and gives hatch dates from March through May.  But I've found these in the fall, winter, spring, and summer in the Rapidan River.  I've found them here and there in a lot of the streams I explore, but I've only seen them in large numbers in the Rapidan River.  Cases vary by genus.  But Brachycentrus is the genus we most commonly find, and their cases are 4-sided, put together in "log cabin" fashion, out of ribbons of bark -- miracles of case composition.  Two examples below, both from the Rapidan River.

5. Limnephilidae, common name "Norther case-maker."  Those pictured below are genus Pycnopsyche.
This is the largest case-maker we normally see (I did not see any "Giant" case-makers (Phryganeidae) this year, though we have found a few in the past in some of our streams.)  The Limnephilid is a "spring" case maker.  I found them this year from the end of March through the beginning of June.  And, they prefer small streams -- really small.   They make a variety of cases which tend to be "genus specific."  But all of the Limnephilids I found keyed out as Pycnopsyche.  Photos below, beginning with my favorite case -- the three-sided case made of precisely cut pieces of leaves.

Other Limenphilid cases (the larvae were hidden inside):

6. Leptoceridae, common name "Long-horned case-maker".  Genus Nectopsyche.
I think of this as a "summer" case-maker, and one that we primarily find in big rivers, i.e. the Rivanna, main stem.  I've found them in other streams -- never small, mountain streams -- but when I want to look for them I head to the Rivanna, and the Rivanna at the bridges at Milton and Crofton.  They get their common name from the fact that they have long, visible, antennae both as larvae and as adults.  The genus Nectopsyche -- the one we commonly see in the Rivanna -- attaches its case to the sides of stems of vegetation.  The cases are very hard to see if you're out, like me, lifting up rocks.  These photos -- not the best -- were taken in June.

7. Odontoceridae, common name "Strong case-makers."  Genus Psilotreta.
This is a case-maker we can find, in theory, just about any time of the year since it has a two-year life cycle.  But, they crawl around on rocks, only in "fall," and that's when we normally see them.   I look for them in September and October.  The cases are very strong and cannot be easily broken.  I've only seen them in two of our streams: the North Fork of the Moormans and the Rapidan River.  This is a very intolerant family, so you'd better look for them in clean, cold, mountain streams.   The photos taken below date from 9/17.

Detailed discussions of all case-maker families were posted in earlier entries.

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