caddisfly larvae at Jackson-Frazier wetlands

[b_g...@comcast.net]

Hi folks,

The water was clear enough at the wetlands on Saturday to get some photos of some developing caddisfly larvae. These are a Limnephilus species, although they are not Limnephilus flavastellus (a common species at the wetlands). To figure out the species, you'd probably have to raise them to adulthood (species ID for caddisflies and many other insects is determined by looking at genitalia, and these don't develop until adulthood). I thought it was interesting that these made their cases out of seeds and snail shells. Does anyone recognize the seeds? Because of the location and general appearance, I thought these might be water parsley seeds, but I can't confirm that.

Cheers,
Bill

[Randy and Pam Comeleo]

Bill -

 

We found similar-looking seeds in some coyote scat at the Malheur Field Station this past fall.  At first we thought they were Colorado Potato Beetle exoskeletons but the Field Station co-director Duncan Evered told us they were Russian (Autumn) Olive seeds.  Is there any Russian Olive in the area?

 

Randy and Pam

Corvallis

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[Lisa Millbank]

Like Bill suggested, I think these are likely to be Water Parsley seeds (see a picture of dry seeds at http://www.prairiemoon.com/image.php?id=1153&type=D).  The seeds attached to the caddisfly larva cases look a bit different since they've absorbed water.  Water Parsley is fairly abundant at Jackson-Frazier, so it's a good bet.

I didn't realize that Russian-olive seeds looked so much like carrot/parsley family seeds, it's really kind of remarkable.  I searched on the Oregon Plant Atlas, and it looks like they are restricted to east of the Cascades, which is a good thing, since it's kind of a problematic introduced plant.  At least some critters enjoy the fruit as shown in your picture!

If these really are Water Parsley seeds, I wonder if they might germinate while they're still part of the caddisfly cases?  Or maybe they have to be in contact with the soil to start growing.

Lisa Millbank
www.neighborhood-naturalist.com 

[John Notis]

While I agree that Water Parsley or a close relative like Dill looks like the best match for Bill's photos, Russian Olive (Elaeagnus angustifolia) is present in the Willamette Valley, and a close relative Autumn Olive (E. umbellata) is more common. I've photographed both while out birding. Both were considered good shelter and food species and were planted for habitat improvement, although I don't know if that was done locally. They are/were also planted as ornamentals and are spread easily by birds and other animals. Both are featured on OSU's landscape plants database, and there is note of a Russian Olive specimen on campus. It doesn't quite make sense that they identify Russian Olive as a native species, and then talk about how it's listed as a noxious weed, brought to the US in the 1800's.

http://oregonstate.edu/dept/ldplants/1plants.htm#elaeagnus

-John

[Don Boucher]

It might be that there isn't enough information in the photos to positively identify the seeds. Water Parsley has tiny seeds (~2-3 mm) while Russian Olive seeds are larger (7-9 mm). So how large are the caddisfly larvae? Maybe a larger photo could show the seed size and texture better?

How likely is it that Russian Olive is growing at this wetland? Does it tolerate rich soil that is saturated most of the year? I've never encountered it there but maybe I've missed them if there's only a few growing?

Don Boucher
Corvallis

[b_g...@comcast.net]

Hi folks,

Thanks for all the input!!
Well...I didn't measure the caddisflies in their cases, but they are still quite young. I'd guess they are about 15mm long. Just FYI there are large amounts of this seed floating on the surface of the water right up against the southwest portion or boardwalk loop. Maybe somebody can grab some seed to measure and/or germinate. If nobody else gets down there right away, I'll try to go this weekend.

Cheers,
Bill

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From: "Don Boucher" <bouc...@peak.org>
To: mid-vall...@googlegroups.com
Sent: Thursday, January 3, 2013 4:12:28 PM
Subject: Re: [MidValleyNature:1770] caddisfly larvae at Jackson-Frazier wetlands

[b_g...@comcast.net]

Hi again everybody,

I went and picked up some of that seed and it is about 2mm long. It's really incredible how much seed is in that one spot. Here's a photo...

Cheers,
Bill

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From: "b gerth" <b_g...@comcast.net>
To: "Don Boucher" <bouc...@peak.org>
Cc: mid-vall...@googlegroups.com
Sent: Thursday, January 3, 2013 5:49:20 PM
Subject: Re: [MidValleyNature:1771] caddisfly larvae at Jackson-Frazier wetlands