caddisfly eggs and cases ~ 07/27/11 ~ Butano

caddisfly egg mass
Trichoptera

I looked at the usual suspects for this area, like California newt or California red-legged frog, but none of the pictures seem to match this egg mass. Each egg did not appear to have any round definition. The whole gelatinous mass was attached to the rock on the top and loose and flat on the bottom. It was roughly a quarter coin in size. When I found it, it was positioned in such a way that half was in the water and half was above water. After taking the above picture, I placed the rock back to about how it was in the water. Anyone have any ideas of what animal laid this egg mass?

edited 08/05/11 - I originally posted this as an unknown egg mass. I initially thought it might be an amphibian egg case, particularly after I had just spotted a CA newt. Thanks to commenter Neil of microecos and Oryctology blogs, I have an answer. Neil has been extraordinarily helpful in identifying things for me and providing information, although I find I have to google about every other word in his blogs to even get a gist of his topics. All I can do is stand back in awe of people whose brains function on that level.

If I had seen an adult caddisfly, I would have been able to identify it to Order without too much trouble. I like to think of Trichoptera as aquatic versions of Lepidoptera. Indeed the two Orders are closely related with adult caddisflies looking very similar to moths. However, there is very little specific information available on caddisfly eggs. The only picture I can find online that looks anything like the egg mass I found is from Bruce G. Margot's taos-telecommunity. I'm hesitant to agree with his guesses to family and genus since I have no way of confirming his IDs. There are other types of caddisflies that lay eggs on leaves instead of rocks. For lovely pictures of egg masses attached to leaves, check out Natura Mediterraneo and manham's Flickr set.

caddisfly larval or pupal cases
Trichoptera

It simply never occurred to me that whatever laid the relatively large egg mass was also the same type of animal that made the gravel clusters seen right next to the eggs on the same rock and all around in Little Butano Creek. I'm guessing these are two different species of caddisflies, but then again, I have no way of knowing for sure. The gravel clusters are protective cases caddisfly larvae make using silk and available materials, such as sand, twigs, or jewels as provided by Hubert Duprat. Depending on the species, they can either live in them through their entire immature stages or make them only to pupate, like a cocoon of sorts. I was hoping to be able to identify the cases since some are distinctive enough to be diagnostic, but that might be asking too much. Aquatic Insects of Central Virginia has a nice posting on saddle-case makers (Glossosomatidae), which was the closest shape of case I could find to match what I saw.

As a side note, you would not believe the amount of e-mail that went on behind the blog scene here. At one point someone sent me a picture of another unidentified case made out of twigs and I forwarded it to an entomologist in Australia. Interestingly enough, caddisflies are not the only insects that make cases from surrounding materials. Bag moths in the Order Lepidoptera and Family Psychidae make startling similar cases, the log cabin shape out of twigs (bag moth vs. caddisfly) and the tubular shape out of sand (bag moth vs. caddisfly). Besides size, the easiest apparent difference is caddisfly cases are usually found in water. If you can manage to get the larvae to peek out, caddisflies have rather long front legs and bag worm caterpillars are short.

This was a really fun post to share. Thanks to everyone who helped out and put in their 2 cents.

ps 09/27/11 - For a good summary of various caddisflies, check out Aquatic Insects of Central Virginia's newest post.

pss 10/03/11 - I'm happy to report this blog post has been included in Circus of the Spineless #66 blog carnival, hosted at Wanderin' Weeta (With Waterfowl and Weeds).