Caddisfly Larvae: All You Need to Know for Identification and Habitat Insights

Caddisfly larvae are fascinating aquatic insects belonging to the order Trichoptera.

They thrive in various aquatic habitats, notably in flowing waters on the bottom surfaces of streams.

These slender creatures have a segmented abdomen, usually concealed within a portable protective case made from tiny pieces of plants, sand grains, or other debris adhered or spun together.

A unique feature of caddisfly larvae is how they create their cases.

Depending on the species, their cases can vary from simple tubes to intricate cones.

Another interesting aspect is their diet, as they are known to filter food particles from water to sustain themselves.

These intriguing creatures play a vital role in their ecosystems and can even be indicators of water quality.

By learning more about caddisfly larvae, we can better understand and appreciate the role they play in maintaining healthy aquatic environments.

Caddisfly Larvae: Basics

Identification and Anatomy

Caddisfly larvae, also known as Trichoptera larvae, are aquatic insects with certain distinctive features. They possess:

• A slender, segmented abdomen
• 3 pairs of legs at the front of their body
• Chewing mouthparts
• A protective case formed from tiny pieces of plants, sand grains, or other detritus

These insects also exhibit long antennae and compound eyes, which are found in many adult caddisfly species.

Habitat and Distribution

Caddisfly larvae can be found in a variety of aquatic environments such as:

• Streams
• Rivers
• Lakes
• Ponds

Their distribution is vast, as they are found in nearly every region worldwide, except Antarctica.

Here’s a comparison table of caddisfly larvae and dragonfly larvae to help you differentiate them:

Life Cycle

Eggs

Caddisfly females lay their eggs in aquatic habitats, such as rivers and streams.

These eggs are typically found encased in a gelatinous mass, providing protection until hatching.

Larval Stage

The larval stage of caddisflies involves these fascinating creatures constructing protective cases for themselves.

They use various materials like plant fragments, sand grains, or other detritus, to create tube or cone-shaped cases that serve as their portable homes¹.

Throughout the larval stage, they consume plant material, algae, and small organisms.

Caddisfly Pupae

Pupa

As caddisflies transition from larva to adult, they undergo a pupal stage where they remain dormant.

During this time, the larval case serves as a protective cocoon where the pupa undergoes metamorphosis. Pupae are mostly immobile and do not feed.

Adults

Adult caddisflies emerge from their protective cases and take on a moth-like appearance, with wings held rooflike over their backs².

A comparison between larvae and adult caddisflies is provided below:

Adult caddisflies have a relatively short lifespan ranging from a few days to several weeks. Their primary focus during this time is mating and reproducing.

Behavior and Ecology

Feeding Habits

Caddisfly larvae are primarily herbivores, feeding on a variety of organic material such as:

• Algae
• Aquatic plants
• Decaying vegetation

Some species may also feed on small invertebrates.

Caddisfly larvae like Brachycentrus spp. filter food particles from the water while housed within their protective cases.

Protective Cases and Structures

Caddisfly larvae create portable protective cases using available materials, like:

• Plant fragments
• Sand particles
• Small stones

The cases are held together with silk, providing a secure shelter for the vulnerable, soft-bodied larvae.

Cases vary in shape and size depending on the species.

Caddisfly Larva Case

All About Silk

Silk plays a critical role in caddisfly larvae’s survival. Functions of silk include:

• Holding protective cases together
• Constructing nets for feeding
• Allowing attachment to stones or plants in freshwater habitats

Silk secretion comes from special glands in the larva’s body, making it a vital component in caddisfly larvae ecology.

Relationship with Environment and Other Species

Water Quality and Pollution

Caddisfly larvae are sensitive to water quality and are often found in clean, well-oxygenated habitats like lakes, rivers, ponds, and marshes.

They serve as indicator species for water pollution, with low numbers suggesting poor water quality.

Pollution tolerance levels:

• High tolerance: Case-making species
• Low tolerance: Free-living and net-spinning species

Role in Food Chain

Caddisfly larvae play a crucial role in the aquatic food chain:

• As consumers: They feed on detritus, algae, and small invertebrates.
• As prey: They are eaten by various predators such as trout, dragonfly nymphs, and birds.

Caddisfly Larvae

Conservation and Habitat Support

Caddisfly larvae contribute to habitat support and conservation in the following ways:

• Water quality maintenance: Their presence can signify good water quality, promoting healthy ecosystems.
• Worcestershire biodiversity: They are part of the diverse species that inhabit Worcestershire’s water bodies.
• Food source: They provide a vital link in the food chain for higher predators.

Key characteristics:

• Aquatic
• Sensitive to water quality
• Indicator species
• Part of the food chain

In conclusion, caddisfly larvae have a significant relationship with their environment and other species.

They are sensitive to water quality and play a critical role in maintaining biodiversity and conservation efforts in aquatic ecosystems.

Understanding their different tolerances to pollution and their role in the food chain can help protect and conserve their habitats.

Caddisflies and Fishing

Caddisfly Hatches

Caddisflies are insects in the order Trichoptera, and they are commonly found in North America.

These aquatic insects are an essential food source for fish and birds, making them popular among anglers.

Caddisfly hatches happen in various periods of the year, with the Mother’s Day hatch being renowned among fly-fishermen, as it often kicks off the spring fishing season¹.

Fly Fishing Tips

When fly fishing for species that feed on caddisflies, it is essential to know a few tips:

• Observe the hatch: Take note of the size, color, and type of caddisfly emerging.
• Match the hatch: Choose a fly that mimics the natural caddisflies in appearance and behavior.
• Fish near the surface: Caddisflies typically emerge close to the water surface, so focus your fishing efforts there.

Popular Bait and Lures

Choosing the right bait or lure can significantly impact your fishing experience. Here are some popular options when targeting fish that feed on caddisflies:

• Peeping Caddis: a type of nymph that mimics a caddisfly larvae in its case².
• Elk Hair Caddis: a dry fly that emulates an adult caddisfly on the water surface.
• Pupa Patterns: representing the transitional stage between larva and adult.

Comparison Table:

Caddisfly Larvae

Caddisfly Larvae in Art and Science

Caddisfly larvae are fascinating creatures. They’re found in aquatic habitats and create protective cases from tiny pieces of plants, sand grains, or other detritus adhered together into a tube or cone.

In art, the intricate cases of caddisfly larvae have inspired artists.

One famous example is Hubert Duprat, who provided the larvae with gold and jewels to create stunning case designs.

Literature on caddisflies mostly consists of scientific research. A notable study centers on Enoicyla pusilla, a rare woodland caddisfly species.

When it comes to science, caddisfly larvae are interesting due to their adaptive spinning of adhesive silk underwater.

These adaptations have practical applications too, like biomimetic materials.

Relationships between small mammals and caddisfly larvae are observed in food chains. Some mammals consume larvae as a food source.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about Caddisfly Larvae.

Scroll down to have a look at some of them.

Letter 1 – Caddisfly Larvae

Pond insect that wraps twigs and leaves around itself
Sun, May 3, 2009 at 4:22 PM
Today, while looking into the pond in our backyard, my husband noticed some movement along the bottom of the pond. Being the curious man he is, he reached in and what he pulled out were these two very strange looking bugs.

The bugs, about an inch in length, look as though they have wrapped leaves and twigs around themselves for camouflage. He brought these bugs into the house and placed them in an isolation chamber in our aquarium for further investigation.

After googling various descriptions of this insect I came out empty. So here I am seeking your knowledge. Attached are three pictures. In two you will see how they seem to like to attach themselves to each other. Hopefully you can help us identify these bugs. Thanks 🙂
Ashley
Southern Ontario, Canada

Hi Ashley,
These are Caddisfly Larvae and they are in the order Trichoptera.  Here is what Charles Hogue writes in Insects of the Los Angeles Basin:  “The larvae, which are aquatic bottom dwellers, are well known to stream fishermen as caseworms. 

Those of most species live in some sort of protective case or tube made of silk, with bits of leaves, twigs, sand grains, pebbles, or other object incorporated into the material to give the larvae additional physical protection and camouflage. 

The shape and method of construction of the case is characteristic for a species or group of species, and the variety in these mobile homes is extensive:  they may be purse-shaped, tubular, curved, snail-shaped, or rectangular, and there are even types with sticks set in an ascending square framework that mimic a little log cabin.”  Adult Caddisflies resemble moths.

Letter 2 – Caddisfly Larva from Australia

strange bug
Hi, I hope this photo is enough for you to help me. I found this bug in some pond water and thought at first it was a small hollow stem but then the stem moved around, looking closely I could see legs coming out of the straw. It stretched out many times but then went back into the stem, like a hermit crab. Can you tell what it is? Thanks,
Sue MacMillan
Adelaide, South Australia.

Hi Sue,
What a wonderful image of a Caddisfly Larva. Caddisflies are in the order Trichoptera. The larvae are aquatic and build homes for protection. Each species has a distinct type of home. Some like yours, use hollow sticks. Others cement sticks or pebbles or shells together.

Letter 3 – Caddisfly Larva

Hi there
I found your website while looking to find out what I caught when I scooped some tadpoles for my kids today. I’m pretty sure it does not look like a stick, but rather it lives in a stick. Legs look a little crabby or crawdad like. I don’t know, here is a picture. I would really appreciate if you had any information.
Thank you
Amanda

Hi Amanda,
Your fascinating insect is an aquatic Caddisfly Larva in the order Trichoptera. Adult Caddisflies are mothlike insects, and the larvae are aquatic shelter builders.

Each species of Caddisfly, and there are many, builds a unique style of casing that it carries around with it for protection. Sone are a single twig, some many twigs cemented together, and some are even cemented pebbles and shells. You can read more about Caddisflies on BugGuide.

Letter 4 – Caddisfly Larva

trying to identify this strange bug
Hello
My 6 yr old discovered this “pupa” while on vacation at her grandmother’s in the BC interior. She was on a creek at the time. Here is a photo.
Monique

Hi Monique,
This is a Caddisfly Larva. Adult Caddisflies resemble moths. The larvae are aquatic and are called Caddisworms. Many species construct portable cases around their bodies which later become pupal shelters. Sticks, small pebbles and other materials can form the basis of the case. Each species has a distinct type of case with specific building materials.

Letter 5 – Caddisfly Larva or Caseworm

Water Bug from Mendocino
Wed, Jul 1, 2009 at 8:09 AM
Hi WTB. I am easily freaked out by bugs but have a strange obsession with your site, as I came across it trying to identify a beetle. I live in Mendocino and was excited to see that you came here, I even joked to my boyfriend I was going to track you down and make you look at my pictures!

Anyway the bug I want identified today was found in the Noyo River last week. I’ve posted two different pictures- It seemed to me it was the same bug, but at different stages in it’s life…? The first pic. is when we put it on land. It was narrow at the butt, wider at the head, with a big whole that it “went into” when it was bugged with.

They both had little stones all over their body. The second picture looked the same, but it had things shooting from its backside. It loo ked like its defense would be to look like some kind of tree fallings. They were found in shallow water on the rocks and once we started looking for them they were everywhere!
P.S. I see easily 25 banana slugs a day if you decide that you would in fact like a pic. of one!
katebell
Northern California- on the Coast

Dear katebell,
These are Caddisfly Larvae. Caddisflies are in the order Trichoptera. Caddisfly Larvae create homes for themselves by cementing stones, twigs, shells and other debris. The larvae are called Caseworms.

According to Charles Hogue in Insects of the Los Angeles Basin: “The shape and method of construction of the case is characteristic for a species or group of species, and the variety in these ‘mobile homes’ is extensive: they may be purse-shaped, tubular, curved, snail-shaped, or rectangular, and there are even types with sticks set in an ascending square framework that mimics a little log cabin.”

There is a picture in Hogue’s book that looks very similar to your examples and it is listed as being in the genus Hesperophylax.  We were in the Mendocino Woodlands campground near Fort Bragg and we are sad you did not try to find us.  We would love a Banana Slug image.  Please title the letter Banana Slug.

Letter 6 – Caddisfly Larva

What is this
Location: Yosemite, CA
August 30, 2011 2:43 pm
Last week we went camping for a few days in Yosemite and while playing in the river I kept noticing that every once in a while bubbles would come out of the sand. While trying to find the culprit I found this strange bug thing that kind of resembles a hermit crab.

At first it looked like it had a shell with a beetle head sticking out of it. But after taking a closer look you see that it’s just a bunch of rocks and stuff stuck to it’s back. It stayed completely submerged under water the entire time we were there.

Never seen anything like it. Picked it up. Took a picture of it and then put it back. I’ve searched on-line but never found anything close to it.
Signature: Super Curious in SoCal

Dear Super Curious,
We were puzzled at first by viewing your photo, but upon reading your email, we are certain that this is the larva of a Caddisfly.  They are frequently called Casemakers or Caseworms because of the shelters that are constructed by the larvae for protection.  Each species of Caddisfly constructs a unique case.  Some use twigs, and others use pebbles or shells for their homes.

Thanks a bunch!  I looked around at Caddisfly information after reading your e-mail and I’m sure that’s it.  It was really weird….it had a head that looked like a beetle and I never knew one could live underneath the water.  Always thought of aquatic bugs as kind of floating around on the surface.  Anyway, your site is great!  Love all the pictures.
Heidi

Letter 7 – Caddisfly Larva from The Netherlands

water insect
Location: Eindhoven, The Netherlands
October 3, 2011 2:12 am
These are crowling on the bottom of my pond in the backgarden. We live in Eindhoven The Netherlands.
Please can you tell me what bug this is?
Signature: Ine Marijke

Dear Ine,
You have photographed the larva of a Caddisfly.  Caddisfly larvae are aquatic and they build cases from various materials, including sand, gravel, shells and twigs.  Each species of Caddisfly builds a different type of case.  Because of this trait, Caddisfly Larvae are frequently called Caseworms.

Letter 8 – Probably NOT Caddisfly Pupae, we NOW suspect

Is this a bagworm?
Location: Fish Hoek, Cape peninsular
October 24, 2011 4:15 am
I found this group under a rock each measures about 8 mm long.
I am in Fish Hoek, Cape peninsular area.
(In Zimbabwe we used to get big bagworms that made their sleeping bags out of thorns etc)
Signature: Brian

Hi Brian,
We don’t know what this is, but we don’t believe they are Bagworms.  Our best guess is perhaps the Pupae of Caddisflies or Caseworms.  The larvae are aquatic and build “homes of sticks, shells or grains of sand.  Each species has a very distinctive case.  Caddisflies also spin silk.  Was this rock overhang near a stream?  If not, then we are most probably wrong.  We hope one of our readers can provide some information.  The North Carolina State University Entomology website has a nice page on Caddisflies.

Hi
Interesting – thanks for the comments!
There is no steam nearby – in fact I on a very rocky and rather dry area of sandstone hill/mountain about 2.5 km from the ocean. (Fynbos)
The drawings on the www.cals.ncsu.edu   website are similar – but I think I will have to ask the local university Zoology Dept
Thanks
Brian

Then Caddisflies must be wrong.  This needs more thought.

Letter 9 – Caddisfly: Snow Sedge we believe

WTB
Location: juneau alaska
November 16, 2011 10:07 am
This bug was found in juneau, Alaska yesterday. Never seen one arround here before let alone we dont see many bugs in the winter!
Signature: Gary

Hi Gary,
This is a Caddisfly in the order Trichoptera.  Caddisflies are mothlike creatures that have aquatic larvae that build cases for themselves.  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 case’s particular shape and construction material is distinctive of the family and/or genus, and can be used in identification.

Example: Helicopyschidae larvae use sand grains to build spiral cases that resemble small snail shells.”  The light markings on the wings of your individual seemed distinctive, so we made an attempt at a more specific identification.  We believe your Caddisfly is in the genus Psychoglypha, and it looks similar to this image posted to BugGuide that contains the comment from Dave Ruiter: 

“The scalloped wing, color pattern and venation are characteristic of several, but not all of the species in this genus.”  Somewhere as we were clicking around, we thought we read a name Snow Sedge, so we did a web search of that term and found the TroutNut website that attributes the name to the genus and provides this information: 

“These caddisflies may be important to the winter angler because they are one of the only insects around. Gary LaFontaine relays an interesting correspondence about this genus in Caddisflies:  Dr. George Roemhild explained to me how he finds these winter caddisflies in February and March:

‘They crawl up on the snowbanks, but when the sun hits their dark wings they melt down out of sight. That’s how I collect them, by walking along looking for holes in the snow.'”  To back check where we found the name Snow Sedge, we searched again, adding BugGuide as a keyword and found this posting on BugGuide.  The presence of Caddisflies is an indication of clean, unpolluted water.  Here is one final photo from the Natural History of Southeast Alaska website.  

Letter 10 – Caseworm: Caddisfly Larva

Subject: Pond Insect
Location: Oak Harbor (Whidbey Island), WA
June 15, 2012 2:26 pm
We started seeing these ”thatched cocoon” things floating in our pond in May. At first I thought they were worms but as they emerged their legs became visible. I’ve never seen anything like it! Any ideas?
Signature: Cyaxtin

Dear Cyaxtin,
Though it is commonly called a Caseworm, your observations that this Caddisfly Larva is not a true worm is correct.  Aquatic larvae are usually called Naiads.  This Caseworm will metamorphose into a winged Caddisfly, a mothlike insect.  This is an awesome photo.  Each species of Caddisfly makes a distinctive looking case because of both the form and the materials used.  The case serves as a shelter during its larval stage.

Thank you soooo much!! Fascinating little creatures! I very much appreciate your time!
Krystal

Letter 11 – Caseworm, AKA Caddisfly Larva

Subject: Water hermit insect
Location: British Columbia, Canada
April 8, 2016 5:34 pm
Hi,
Found this bug in the water. It likes to flap it’s long body to get around as if someone tied it to a chair. It’s quite hilarious. Wondering what it’s diet is as well.

It seems to have a long body and white (mini legs) along its body which is noticeable when it comes out to swing itself around. Kind of reminds me like a wormlike-roach in water but I really don’t have an idea what this creature is. Thanks!
Signature: R.

Dear R.,
This is a Caseworm, the aquatic larva or naiad of a Caddisfly, a mothlike insect from the order Trichoptera.  According to BugGuide:  “The aquatic larvae have three pairs of legs and a soft, elongate, segmented abdomen usually hidden inside a case; head well-developed with chewing mouthparts in most species. 

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 case’s particular shape and construction material is distinctive of the family and/or genus, and can be used in identification. Example: Helicopyschidae larvae use sand grains to build spiral cases that resemble small snail shells.”

Wow, neat. Thanks for your response Daniel!

Letter 12 – Caseworm or Caddisfly Larva

Subject: Stick looking bug in a stream
Location: Bridgeport, CA
August 21, 2016 10:48 am
I found this bug crawling in the water in a stream near Bridgeport, CA.
Signature: Leonard Powell

Dear Leonard,
This is a Caddisfly Larva, commonly called a Caseworm.  Each species of Caseworm constructs a case for protection that looks distinctly different from the cases of other species of Caddisfly.  The cases may be constructed of sticks, shells, sand, or other debris.

Letter 13 – Caseworm and the Metamorphosis of Tadpoles

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.

Letter 14 – Caseworm or Caddisfly Larva

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.