The mask is the tell. The 'tails' on a damsel nymph are gills.
First checkLook at the mouth. If you can see a grasping mask, you are in Odonata.
Odonata nymphs are predators. The extendable labium — the mask — is the strongest field separator from mayfly and stonefly.Dispute
Damselfly nymphs are slender with three leaf-like caudal lamellae. Those lamellae are commonly misread as mayfly tails. Look at the shape: flattened and leaf-like, not round filaments.Dispute
Dragonfly nymphs are robust and lack those external lamellae. Adults hunt over stillwater and slow margins.Dispute
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 Damselfly / Dragonfly
Extendable grasping mouthparts (labium / mask) on an aquatic nymph+6
Three leaf-like caudal lamellae at the tail (damselfly nymph) rather than round filaments+5
Three tail filaments clearly visible+1
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
Portable case or case-like structure present-4
Pinched waist (ant / flying ant) with elbowed antennae-4
Hard wing covers (elytra) meeting in a straight line down the back-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Head withdrawn into the front of the body, hard to see-4
A single tail filament pointing straight back, and no paired hooks-4
Fallen terrestrial insect (hopper, ant, beetle, etc.) — not an aquatic emergence-3
Hopper / grasshopper silhouette — hind legs long, body blocky, wings folded along back-3
Air bubble or silvery film carried under water (diving beetle / water beetle)-3
Swollen rear end gripping a rock in current, body standing up and waving downstream-3
Two tail filaments clearly visible-2
Hardened head with softer worm-like abdomen-2
Terminal prolegs or hooks at the rear-2
Plate-like or feather-like abdominal gills visible-2
Gills at the thorax or leg bases-2
Wings held tent-like or inverted-V over body-2
Two long antennae-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 →
Over stillwater, slow margins, and bank vegetation.Dispute
How it moves
Dragonflies: strong, sustained flight. Damselfly flight is called weak and fluttery by one source and fast by another.NOAA-GLERL-ODONATA, MDC-DAMSELFLIESDispute
Cues this stage offers the comparison
Winged insect at or near the surface
Wings held flat and parallel along the body
Confused with
Telling it from what it isn't.
Damselfly / DragonflyvsMayfly
Mayfly cerci are round filaments; damsel lamellae are leaf-like gills. The labium mask settles Odonata.
These groups name Damselfly / Dragonfly in their own separators. If you arrived holding one of them and were not sure, this is the sentence that pointed you over.
Where in the column it mattersMid column. Climbers live in the weed, burrowers in the bottom. Damselfly nymphs can also swim by undulating the body, and mature nymphs crawl out of the water to emerge.
Read from the record's own position notes: among vegetation and stems (climbers); on or in substrate (sprawlers / burrowers); adults hunting over stillwater and slow margins.
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
Nymphs presentnymph
JFMAMJJASOND
Damselfly and dragonfly nymphs can take a few years to mature, so they are in the water all year, long before adults hunt the margins.
Observed: Missouri field guide; development time varies with species.
The pattern layer ties this group in Nymph. 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.
Damsel Nymph
Nymph
Hook10–16
A slender damselfly nymph with leaf-like gills at the tail, not three filaments.
Slow-stripped through weeds. The pause is when a damsel nymph actually moves.
Dragonfly Nymph
Nymph
Hook4–10
A stout dragonfly nymph — the mask is the structure, the bulk is the rest.
Crawled along the bottom or stripped in short hops off weed edges.
6 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 reviewerBroad order only. Not a family or species call.Dispute
Declared by the reviewerNo current emergence or density claim.Dispute
Declared by the reviewerOdonata is a broad order. This record supports a damselfly/dragonfly hypothesis, not a family or species call.Dispute
Declared by the reviewerCaudal lamellae on damselfly nymphs are commonly mistaken for mayfly tails; the labium mask is the honest separator.Dispute
Declared by the reviewerThis preview does not claim a current emergence, density, or fishing pattern.Dispute
Sources disagreeNOAA GLERL describes damselfly flight as weak and fluttery; the Missouri Department of Conservation describes it as fast. Both describe dragonfly flight as strong.
Sources
Everything above rests on 7 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.
Leaf Pack Network. Both nymphs swimming in the same clip: jet propulsion against three caudal lamellae sculling. That is this entry's whole internal split.
Research institute · external video · title read back from the publisher 2026-09-09
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