The comparison scores every group at once. This page is for the moment you already have a pair of names in mind — mayfly or stonefly, scud or sowbug, shad or alewife — and want the structures that keep them apart, in one look. Nothing here is a current hatch.
The differences, and nothing else
Best separating check: Winged insect at or near surfaceWhere it was It separates Cranefly larvae from Midge (non-biting) cleanly, and every pair of groups still in play differs on it and you can check it at a glance.
What to look at
Cranefly larvae
Midge (non-biting)
Head withdrawn into the front of the bodydecisiveClose look
Yes
No
Fleshy lobes or a disc at the blunt reardecisiveClose look
Yes
No
Hardened head with softer worm-like abdomendecisiveClose look
No
Not diagnostic
Terminal prolegs or hooks at the reardecisiveClose look
No
Not diagnostic
Winged insect at or near surfacedecisiveWhere it was
classified as a crawler and burrower; no source consulted describes how it actually moves
wriggling or undulating; anchored by posterior prolegs
Reference seasonality
No family-level window
Emergence: Jan, Feb, Mar, Nov, Dec
Rows come from the reviewed diagnostic weights the comparison scores with. “Decisive” means one answer puts them at least four points apart — the carrier's own rule for a structure that separates a pair.
The two entries, side by side
Diptera (Tipulidae)
Cranefly larvae
A grub with nothing to walk on and a head it keeps to itself.
First check
Look for legs. None at all, on a plump segmented grub, means a fly larva. Then look at the blunt back end for a disc ringed with lobes.
What it is
A cranefly larva is a plump, blunt, segmented grub, tan to grey to greenish, with a dark line of gut showing through the skin. It has no legs — and that is not a small observation, because one state assessment guide puts the whole order behind it: flies are the only aquatic insect whose larvae lack fully developed legs. If you can see three pairs of jointed legs, you are not holding one of these.
Stages
Larva (3–60 mm across the consulted sources, which disagree substantially)
Water
stream, river, lake-margin, spring, reservoir
Separates from Midge (non-biting)
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.
Typical windows
No family-level window in this layer.
Patterns (correspondence)
None mapped yet.
Limits
Sources disagree about the head: Missouri says the larvae have a definite head; WVDEP says it is often reduced and barely visible, and a university key notes the thorax often has to be cut to see it. This entry follows the second.
Small, everywhere, and the reason a dead-looking river isn't.
First check
No true legs and no long tails. If you see jointed legs or filaments, look somewhere else in the guide.
What it is
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.
Stages
Larva (2–20 mm (New Mexico State gives up to 12.5 mm)) · Pupa (No source consulted gives a pupal size) · Adult (2–12 mm)
Water
river, stream, lake-margin, spring
Separates from Cranefly larvae
This entry does not name Cranefly larvae as a look-alike. That is a gap in the prose, not proof they cannot be confused.
