Tag Archives: larvae

Caddisfly larvae: hippie homesteaders of the streams

Let’s review your friends and acquaintances. They mostly live in houses, take regular showers, enjoy the occasional dinner out, and go with the societal flow, right? 

But you know that guy…

That guy . . .

The one who constructed a home out of logs he cut himself and Styrofoam chunks he pulled off a riverbank? Who eats only what’s in season and criticizes places with too much pollution? And that same person, when they’re not surveying the back 40, probably occupies himself with crafts like spinning his own thread or making jewelry . . . got that image in mind?

See, if you lived in a stream, “that guy” would be a caddisfly larva.

In fact, it’s kind of hard to tell the two apart . . .caddisfly infographic


Your hair is everywhere: First off, the caddisfly order Trichoptera is Greek for ‘hairy wing,’ and you knowww how the treehugger type loves being hairy. The Caddis part means cotton or silk; in Elizabethan era, “caddice men” (vendors of ribbons, braids, etc.) pinned their goods on their coats.

Casemaker, homesteader, potato potahto: When these creatures spin a silk case or cocoon around themselves, they also tie on nearby debris — sand, rock, twigs, leaf pieces, shells. The cases are functional, allowing water in and out over the larval gills. They’re sturdy, sometimes weighing the creatures down in the current.

In a couple of years, the caddisflies’ descendants will point to those little cases trembling in the riffle and say, “My grandfather built this house with his own six hands, with material right from this stream!” Everyone will be impressed.

Equal rights for every invertebrate! There’s a sad side to this industrious behavior. As often happens in global markets, so too are humans are exploiting caddisflies for commercial purposes. In this case, to make jewelry at a high markup. Artists just plop the little larvae in an aquarium filled with gold flakes, pearls, and precious stones, and the caddisflies do the rest. We have to admit, the results are pretty stunning:


Can I have the reverse osmosis water, please?: Another value of the caddisflies is their exacting taste in water. According to this Biomonitoring Macroinvertebrates site, “They breathe dissolved oxygen by diffusion across their soft tissues, and they have a limited ability to cope with low dissolved oxygen by wiggling their bodies within their cases. However, they lack the ability to breathe atmospheric oxygen that some other more tolerant insects have.”

So if you find a caddisfly larva in your stream, congratulations! You have a stream worthy of an eco-snob’s standards. I know I was excited when I spotted this little guy at Clifty Creek Conservation Area in Dixon in February:

Take it easy, man: Finally, it’s just easy to admire the caddisfly larva’s mellow take on life. When it comes to building houses, they work with what they’ve got. They eat what food’s available to them and are willing to change their munching style to do so. They can live in ponds, lakes, rivers, streams, whatever’s fresh. And they are willing and accepting, for goodness sake, to completely metamorphose into an entirely new body at the simple change of a season. Enlightened? Check. Good head on their shoulders? Check. Ain’t nothing wrong with being a hippie, Mr. Caddisfly. You keep on doin’ you.

More information

The Beginner’s Guide to Caddis

Bug Guide on Trichoptera’s 1,350+ species

 P.S. – Huge thanks to Mark Haim for letting us use his image in this graphic. And thanks to the caddisfly, too, wherever you are.

Things to know before you date a Water Penny Beetle Larva

Photo from the Marietta College Department of Biology and Envrironmental Science

Water Penny Beetles are in a family called Psephenidae, under the genus Psephenus, which comes either from psephenos (ψεφηνος), meaning ‘dark, obscure’, or psephos (ψηφος), ‘a small round worn stone, pebble.’ Our money’s on the pebble, because that’s what the larvae look like. Or a penny. A tiny penny for dolls.

In case you’re thinking of taking a water penny beetle out on the town, here’s what you should know:

Favorite food: Microscopic organisms and algae salad.

Where they hang out: Swift currents in streams worldwide.

Personality: Kind of fussy. Sensitive to light, inorganic sediment, and too much algae. They cling to grassy clumps and the underside of rocks in the daytime. At night, they eat on top of the rocks: think, “outdoor balcony, after-hours in a posh restaurant.” The adults don’t live long, so after metamorphosis they mostly let the good times roll and mate a lot: scientists have observed females laying 400-600 eggs in a single patch. They really love oxygen and can’t tolerate pollution.

Which means: Water penny larvae have good taste and live in high-quality streams.

Which is too bad for them because: They make yummy treats for fish living in those high-dollar neighborhoods.

But good for us because: Their presence tells us when a stream is healthy. And they make free fish food.


For more information, visit UW-Milwaukee: Field Station Bug of the Week, the Tree of Life Web project entry on Psephenidae and the 1971 classic, “Ecology of the Water Penny Beetle (Psephenus Herricki)” by Chad M. Murvosh.