Small, everywhere, and the reason a dead-looking river isn't.
First checkNo true legs and no long tails. If you see jointed legs or filaments, look somewhere else in the guide.
Chironomidae is enormous — more than 7,300 described species worldwide, found in every kind of water, including salt water. It is also the group most often written off, because everything about it is small.MDC-MIDGES, NMSU-EXT-CR677-BENTHICDispute
The larva is the giveaway: a soft, segmented, worm-like body with a distinct hardened head capsule, a pair of prolegs under the head and another pair at the tail, and no segmented true legs anywhere. Collected in a tray it usually curls into a C or J. The blood-red forms people notice get their colour from haemoglobin and live in bottom sediment; colour is common but not diagnostic.WV-DEP-BENTHIC-GUIDE, NMSU-EXT-CR677-BENTHIC, MDC-MIDGES, MACROINVERTEBRATES-ORG-CHIRONOMUSDispute
The pupa swims actively up to the surface, where the adult emerges and leaves the empty skin floating. Adults are delicate and two-winged, and males gather in swarms in the air, often in the early evening over a bush, a pool or some other marker.JOVE-CHIRONOMID-PUPAL-EXUVIAE, MDC-MIDGESDispute
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 Midge (non-biting)
No long tail filaments visible+4
Hardened head with softer worm-like abdomen+1
Terminal prolegs or hooks at the rear+1
Winged insect at or near the surface+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
Three tail filaments clearly visible-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
Swollen rear end gripping a rock in current, body standing up and waving downstream-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
Two tail filaments clearly visible-3
Portable case or case-like structure present-3
Plate-like or feather-like abdominal gills visible-3
Fleshy lobes or a disc at the blunt rear end-3
Head withdrawn into the front of the body, hard to see-3
A single tail filament pointing straight back, and no paired hooks-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 long antennae-2
Wings held upright (sailboat posture)-2
Wings held tent-like or inverted-V over body-1
Wings held flat and parallel along the body-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 →
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 midge larva is a worm of even thickness, free-living or in a soft tube, gripping at most with small hooked prolegs. A black fly larva has a swollen rear end hooked into a silk pad on the rock, and faces downstream.
These groups name Midge (non-biting) in their own separators. If you arrived holding one of them and were not sure, this is the sentence that pointed you over.
Leechsaid
A hard head capsule and prolegs at each end is a midge larva, which is an insect. A leech has neither.
A hard dark head clearly out in front, a thin worm-like body and two pairs of hook-tipped prolegs is a midge. Bright red points that way too. Size and habitat separate nothing here.
Where in the column it mattersIn the substrate. Larvae in the sediment, pupae hanging in the film. Midges occupy the whole column at some point in the day.
Read from the record's own position notes: subsurface in sediment or on vegetation; drifting; surface film (emergence).
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
Most of the midge life cycle is spent as a larva, so larvae are in the water in every month. They do not emerge to become available — they already are.
Some midges emerge in winter: at least 11 species emerge from December to February in Minnesota. The best-studied, Diamesa mendotae, is most abundant in groundwater-fed streams.
Observed: Winter-emerging species (mostly Diamesa) in groundwater-fed Minnesota trout streams; other midges emerge in other seasons.
The pattern layer ties this group in Nymph, Dry, Emerger. 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.
7 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 reviewerChironomidae is an enormous and morphologically diverse family; this supports only a broad non-biting midge hypothesis.Dispute
Declared by the reviewerBlood-red forms get their colour from haemoglobin; colour alone is not diagnostic.MDC-MIDGESDispute
Declared by the reviewerThis guide never claims a current hatch, density, or correct pattern. Size and the absence of insect tails or cases are the strongest field separators.Dispute
Declared by the reviewerChironomidae is an enormous and morphologically diverse family; this record supports only a broad non-biting midge hypothesis.Dispute
Declared by the reviewerThis preview never claims a current hatch, density, or fishing pattern. Size and absence of insect tails/cases are the strongest field separators.Dispute
Sources disagree[object Object]
Sources
Everything above rests on 10 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.
Sport Fishing on the Fly. A pupa ascending and then hanging vertically in the film. That pause at the meniscus is the stage, and it is the one thing a side-view drawing flattens away.
Specialist angling channel · external video · title read back from the publisher 2026-09-09
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