Not every caddis builds a house, and the ones that don't are the ones you miss.
First checkIgnore the case. Look for a hard dark head against a soft pale abdomen, and hooks at the back end.
Caddis is the group most often identified by a thing that is only sometimes there. The portable case — grains of sand, cut leaf, twig fragments, spun into a tube the larva carries — is the classic image, and when you find one the call is easy. But a large share of caddis larvae never build a portable case at all. Free-living forms hunt loose among the rocks; net-spinners build a fixed retreat with a catch-net beside it and leave the retreat behind when disturbed.NMSU-EXT-CR677-BENTHIC, NCSU-ENT425-TRICHOPTERA, MACROINVERTEBRATES-ORG-HYDROPSYCHEDispute
So the reliable caddis larva signal is not the case. It is the body plan: a hardened, darker head and forward thorax against a soft, pale, often worm-like abdomen, three pairs of legs clustered up near the head, and a pair of hooked prolegs at the tail end that grip rock, net, or case.WV-DEP-BENTHIC-GUIDE, NOAA-GLERL-WATER-LIFE-FIELD-GUIDE, NCSU-ENT425-TRICHOPTERADispute
The winged adult is a different silhouette entirely — hairy wings folded tent-like or in an inverted V over the body, and a moth-like flutter rather than a mayfly's upright drift.NCSU-ENT425-TRICHOPTERA, MDC-CADDISFLIESDispute
The tell
What settles it, and what settles against it.
Read off this record's own diagnostic weights, heaviest first. A structure near the top of the left column does most of the work on its own; one near the bottom only leans.
Argues for Caddisfly
Portable case or case-like structure present+5
Hardened head with softer worm-like abdomen+4
Terminal prolegs or hooks at the rear+4
Wings held tent-like or inverted-V over body+4
No long tail filaments visible+1
Winged insect at or near the surface+1
Aquatic insect crawling on rock or debris+1
Argues against it
Fish-shaped forage silhouette (minnow / shiner / fry) — not an insect-5
Fallen terrestrial insect (hopper, ant, beetle, etc.) — not an aquatic emergence-4
Moving as a school or tight bait cluster, not as a single insect-4
No hardened head capsule and no legs — soft and segmented throughout-4
One pair of long, flattened, oar-like hind legs used to row-4
Swims on its back, belly upwards-4
Mouthparts form a pointed beak rather than chewing jaws-4
Fleshy lobes or a disc at the blunt rear end-4
Head withdrawn into the front of the body, hard to see-4
Hopper / grasshopper silhouette — hind legs long, body blocky, wings folded along back-3
Pinched waist (ant / flying ant) with elbowed antennae-3
Hard wing covers (elytra) meeting in a straight line down the back-3
Extendable grasping mouthparts (labium / mask) on an aquatic nymph-3
Three tail filaments clearly visible-3
Wings held upright (sailboat posture)-3
Wings held flat and parallel along the body-3
A single tail filament pointing straight back, and no paired hooks-3
Swollen rear end gripping a rock in current, body standing up and waving downstream-3
Air bubble or silvery film carried under water (diving beetle / water beetle)-2
Three leaf-like caudal lamellae at the tail (damselfly nymph) rather than round filaments-2
Gills at the thorax or leg bases-2
Two tail filaments clearly visible-1
A structure at −4 or below is treated as a hard exclusion by the comparison tool rather than as a penalty: if you saw it, this group is ruled out and no amount of matching elsewhere brings it back. Run a comparison →
Moth-like appearance, but held tight rather than flatDispute
Where it turns up
On streamside vegetation, on the water during egg-laying, and in the air over riffles at dusk.Dispute
How it moves
Weak, fluttering flight. Egg-laying females of some net-spinning caddis swim down to lay on the bottom, which is why a sunk adult is not a contradiction.NCSU-ENT425-TRICHOPTERA, USGS-HYDROPSYCHE-REGULATED-RIVERSEvidence from: Diving oviposition documented for net-spinning Hydropsychidae (Colorado River Basin)Dispute
Cues this stage offers the comparison
Wings held tent-like or inverted-V over body
Winged insect at or near the surface
No long tail filaments visible
Confused with
Telling it from what it isn't.
CaddisflyvsMayfly
Wing posture at rest settles it: caddis tents its wings over the body, mayfly holds them upright like a sail.
Stonefly adults hold their wings flat and parallel along the body, not tented. Stonefly nymphs have two long tails and two long antennae; caddis larvae have neither.
At arm's length on a stone, a grit-built caddis case and a snail shell look the same. Pick it up: a caddis case has a jointed head and legs coming out of the front, a snail has a soft foot that grips your finger.
These groups name Caddisfly in their own separators. If you arrived holding one of them and were not sure, this is the sentence that pointed you over.
Midge (non-biting)said
A classic architectural portable case of sand or cut leaf is caddis. Most midge tubes are simple fixed shelters; portable midge cases exist but are far less common.
A caddis case is built of glued grit and has a jointed head and legs coming out of it. A clam is a shell the animal grew, with nothing coming out but a foot.
Where in the column it mattersNear the bottom. Larvae are on or in the bottom; the pupa crosses the whole column to emerge, which is why the ascent matters more than the resting place.
Read from the record's own position notes: subsurface (larva/pupa); surface or near-surface (emergence); resting with tent wings.
Reference windows
When this group is typically available.
Typical published ranges only. Elevation, latitude, tailwater release and a given year's weather move all of these, often by weeks. This is never a statement about today.
2 reference windows
Larvae presentlarva
JFMAMJJASOND
Cased and free-living larvae are in the water all year; the winged adults live only a few weeks.
The pupa develops sealed inside its case, then cuts its way out and swims to the surface to emerge. Missouri's field guide says this is usually in fall. No agency or university source consulted dates spring or summer emergence at family level; the missing bars are a gap in the sources, not a statement that it does not happen.
Observed: Missouri (Missouri Department of Conservation); autumn emergers also documented in coastal Oregon.
No reviewed dossier names this group. That is an absence in the dossier layer rather than a finding about the animal — four dossiers exist and only one of them names any forage group at all.
The pattern layer ties this group in Nymph, Dry, Emerger, Pupa. That is a correspondence between an imitation and an animal, worked out when the patterns were written. Whether a fish is on it today is a question this page cannot reach.
Elk Hair Caddis
Dry
Hook12–20
An adult caddis at rest with its wing tented over the body.
Dead-drifted, or twitched and skated to suggest egg-laying movement.
X-Caddis
Emerger
Hook14–20
An emerging caddis still hung in its trailing shuck.
Fished in the film. The trailing shuck is the whole point of the pattern.
Sparkle Pupa
Pupa
Hook12–18
A rising caddis pupa carrying a gas bubble under its pupal skin.
Swung or lifted through the last of the water column rather than dead-drifted.
Green Rock Worm
Nymph
Hook12–18
A free-living caddis larva tumbling loose in the drift.
Dead-drifted on the bottom. Tied curved to suggest the larva's natural hook shape.
8 of them. The limits are part of what was reviewed rather than a disclaimer bolted on afterwards. An entry that hid them would be claiming more than it checked.
Written by the reviewer
Declared by the reviewerCase-building behavior varies and absence of a visible case does not rule out caddis.Dispute
Declared by the reviewerThis guide does not claim a current emergence or recommend a specific pattern as correct.Dispute
Declared by the reviewerBroad group only; many families exist and differ substantially.Dispute
Declared by the reviewerThis preview does not claim a current emergence or recommend a specific pattern.Dispute
Declared by the reviewerBroad group only; many families exist.Dispute
Sources disagree[object Object]
Sources disagree[object Object]
Read off the record
Nobody typed these. They are fields that are empty, said out loud rather than left for you to notice from a section that simply is not there.
What eats itNo reviewed species dossier names this group. Some dossiers describe forage in class terms — small forage, insects, bait — and those are shown below, but a class description is not a reviewed link to this group and none is claimed.
Sources
Everything above rests on 12 published pages.
These are every page behind this entry. Where a reviewer traced a line above to the pages that carry it, that line names them itself, with where the evidence comes from when it is narrower than the whole entry. A line with no names beside it rests on this list as a whole: nobody has yet checked which page carried it, and naming one would be a mapping nobody made.
A plate shows shape. It cannot show a gill beating, a mask firing, or an animal reversing into sand — so where motion is the field mark, the entry points at motion. These are demonstrations, selected by hand and by publisher. Nothing here is a source: it changes no score, no window and no reviewed claim.
Deep Look. The larva spinning silk and building its case underwater, which is what makes the portable case a behaviour rather than an ornament.
Science media · external video · title read back from the publisher 2026-09-09
Carry it on
Take the group to the next step.
These send the class of animal and the water this record is documented in. They do not send a sighting, because this page does not have one — you have not told it what you saw.
Which fish in this kind of water are documented eating this class of forage, and how they behave when they are.
What this forage class asks of the setup — the weight it wants, and where the chain gives first.
Keep the group on the day's record, so a later entry can be compared against what you were looking at.
Found an error?
This entry was written and drawn away from your water. If something here is wrong, say so — the report is assembled in your browser and sent only if you send it.
