Currently viewing the category: "Caddisflies"

Subject:  found in water
Geographic location of the bug:  Minnesota
Date: 02/11/2018
Time: 01:55 AM EDT
Your letter to the bugman:  Found this bug came up my ice fishing hole looks like it is connected to a stick
How you want your letter signed:  any


Dear Any,
This is the aquatic larva of a Caddisfly, commonly called a Caseworm because the larva constructs a shelter from twigs, pebbles, shells or other materials as a means of protection.  Each species of Caddisfly constructs a different looking shelter.

Subject:  What is this creature?
Geographic location of the bug:  Hartford County, Connecticut
Date: 09/24/2017
Time: 08:55 PM EDT
Hellooooo Bugman. It’s great to see your site as active as ever. I sent you an inquiry years ago and you were able to help. Thank you! Could you please help again? We have been seeing several of these guys and I thought they were roaches at first! The body looks more like a moth to me, but the antennae look more like a beetle. The wings stand up at an interesting angle.
How you want your letter signed:  Thanks again! Annie


Dear Annie,
This is a Caddisfly, and your observation that it resembles a moth is understandable.  Entomologists tend to agree that the Caddisfly order Trichoptera does share many similar traits with the Moth order Lepidoptera.  Do you live near a body of water?  The nymphs of Caddisflies are aquatic and they are commonly called Caseworms.

Subject:  Autumn Brown Bug
Geographic location of the bug:  New Brunswick, Canada
Date: 09/16/2017
Time: 08:34 AM EDT
These bugs just started coming around recently as the weather starts to change these bugs started to come around everywhere!! What are they?!
How you want your letter signed:  Thanks, Danielle


Dear Danielle,
This is a Caddisfly in the order Trichoptera.  Caddisfly nymphs are aquatic and they are frequently called Caseworms as they construct often elaborate protective cases from twigs, sand and shells.  Since the nymphs are aquatic, we suspect you live near a body of fresh water.  Your submission is the second we are posting this morning from New Brunswick, Canada

Subject: Aquatic bug?!
Location: Glacial river, base of mt Rainier
July 31, 2017 8:24 pm
Hello! We were out playing in a very cold glacial river at the base of Mt Rainier in Washington state and came across these guys today. There were hundreds of them on rocks in the water, but only a few this sprawled out and large outside the water.
Signature: Alexa

Stonefly Exuvia

Dear Alexa,
Your images document two different, unrelated aquatic insects.  The image of the one “sprawled out and large outside the water” is actually the exuvia or cast-off exoskeleton of a Stonefly, and the “hundreds of them on rocks in the water” are Caseworms, the larvae or naiads of Caddisflies.  Larval Caddisflies are known as Caseworms and according to BugGuide:  “Most species live in a mobile case constructed from plant material, algae, grains of sand, pieces of snail shells, or entirely of silk. The case is held together with strands of silk secreted by the larva. In some species the case is attached to a rock, log, or other underwater surface; a few species have no case and are free-living.”  The cases on your individuals appear to be constructed using grains of sand or small pebbles.

Caseworms: Caddisfly Naiads

Caseworms: Caddisfly Naiads

Subject: Bug ID
Location: Bridger Mountains, Montana
January 24, 2017 4:00 pm
This bug was found outside of Bozeman, Montana, in the Gallatin National Forest. A nordic skier was skiing down an unplowed road and saw the bug walking on top of the snow. Nearby tree species include Douglas-fir, Engelmann spruce, lodgepole pine, and subalpine fir.
Signature: Johanna Nosal

Snow Sedge

Dear Johanna,
This is a Caddisfly, an insect in the order Trichoptera that is generally found near a source of fresh, clean water because their larvae are aquatic nymphs sometimes called Caseworms because they build protective covers from sticks, stones or shells.  It is our understanding that Caddisflies found in the snow are known as Snow Sedges.  We found this reference to a Snow Sedge on BugGuide, however the information page for the genus on BugGuide does not indicate Snow Sedge is a common name.  TroutNet does identify Snow Sedges and has this to report:  “These caddisflies may be important to the winter angler because they are one of the only insects around.”  Your posting has inspired us to create a “Snow Bugs” tag because we have numerous postings in our archive of insects in the snow, though it was not until now that we decided to organize them together into a dedicated data base.

Caddisfly in the Snow

Subject: Water Bug
Location: Western New York
October 21, 2016 3:20 pm
One of our class room got tadpoles from Africa. The water they put into the tanks was from a pond in one of the teachers backyard. This bug popped up in it yesterday it has a grass straw that it looks like it breathes out of not sure though, and it’s body is protected by this grass looking shell (I guess to camouflage it?) I’ve Googled it and can’t find it anywhere! Thank you in advanced
Signature: -school custodia



Dear school custodia,
Were we betting on the origin of this Caseworm, the aquatic larva of a Caddisfly, we would put our money on the pond in the teacher’s backyard and not that they came in with the tadpoles, but we can’t help but to wonder if one of your classrooms wanted to observe the metamorphosis of tadpoles into frogs, why didn’t they choose to observe a local species of frog rather than to import tadpoles from Africa?  This classroom experiment is going to result in frogs and we hope someone doesn’t decide to release the African frogs into the local pond at the end of the experiment.  Introduction of non-native species into the environment is one of the biggest threats to the survival of native, endemic species in our current climate of globalization.  Alas, we digress.  It was not our intention to lecture your school on the ethics of globalization when you asked about the identity of the Caseworm.  Every species of Caddisfly has a distinctly different Caseworm.  Some make their cases from sticks, some from shells of molluscs, some from pebbles and some from sand.  In our mind, a much more interesting experiment would be to observe the lives of creatures in your local ponds.  Oops, we started lecturing again.

The frogs will be sent back once project is done. They chose this species because of its fast life cycle from tadpole to frog.
And thank you it is a very interesting water bug! The class will be watching it’s life cycle as well 🙂

Thanks for the reassurance.