Little Black Caddis (Chimarra atterima)

Caddis, hatching April–May, active in water between 46 and 58°F, and imitated at #16–20. Recorded from the Wisconsin driftless, where 364 Wisconsin rivers on this site carry a page.

A small, very dark caddis — nearly black body, dark grey wings, size 16 to 20 — that comes off in the same cold weeks as the Hendrickson and is easy to write off as a midge. The peak is April and May, in water from 46 to 58 degrees, which covers only the cold and cold-transitional classes. Chimarra spins a fixed net on rocks in fast water rather than carrying a case, so the larva stays put in the current. The pupa rises fast to the surface, and the swung wet is the classic answer to it. The adult is dark, small and skittering, present in numbers on April afternoons. A dark soft-hackle swung on the tail of a run is the simplest way to fish the emergence: a Partridge and Orange Soft Hackle at 12 to 18 does that work. A CDC Caddis, 14 to 20, or an Elk Hair Caddis, 12 to 20, covers the adult, and a Zebra Midge at 18 to 24 sits alongside for the confusion the size invites.

#16–20Hook size
46–58°FWater, active
Apr–MayPeak months
3Life stages fished

Subbasins with trout water where it is on record: 7 of Wisconsin's 43.

See Wisconsin's trout water on the live map → Every reach coloured by water temperature — the water these hatches come off.

What it is

Caddis · Chimarra atterima · larva → pupa → adult

A small, very dark caddis — nearly black body, dark grey wings, size 16 to 20 — that comes off in the same cold weeks as the Hendrickson and is easy to write off as a midge.

Small, dark, and everywhere in April. A dark soft-hackle swung on the tail of a run is the easy way to fish it.

When it hatches

Peak is April–May. The pale months either side are the shoulder — the app widens a peak by one month in each direction and recommends the bug there, and no further: that widening is bounded so that a bug peaking in May is never offered in August.

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peak shoulder not recommended

Water conditions

The band is a water temperature, not an air temperature, and it is the range in which this insect is worth fishing — for a mayfly that is the emergence window; for a scud or a midge it is simply the range trout will still eat one in.

46°F 58°F

Active from 46°F to 58°F. On this map that is cold, cold-transitional water — the band crosses 1 of the three break the river colours use. Breaks at 58, 64 and 70°F.

Stages

What the insect is doing, and what that means for what you tie on.

Stage	What it is
larva	Chimarra spins a fixed net on rocks in fast water rather than carrying a case.
pupa	Rises fast to the surface. The swung wet is the classic answer.
adult	Dark, small, and skittering. Present in numbers on April afternoons.

Matching flies

5 patterns in this book imitate the Little Black Caddis, across its stages. Which one to tie on follows the stage the water temperature says it is in — the app makes that call on a live reading; this page lists the whole set.

Where to find it right now

The rivers with a page here that sit in this insect's regions, with a USGS gauge reporting water temperature. This list is re-ranked against the reading each gauge is sending now and today's date, so it is live — the fallback below it, if the readings do not arrive, is each river's measured July mean.

Regional presence

Regions, not collection records. This insect is recorded from the coarse regions below; nobody has surveyed which named river it has been caught on, and this page will not pretend otherwise.

northern lower Michigan MI
southern lower Michigan MI
the Wisconsin driftless WI
the Virginia mountains VA
the North Carolina mountains NC
southeast Minnesota MN

Rivers in these regions with a page here

Related hatches

Same family, or overlapping this one's calendar on the same water.

Open the trout map →Every trout stream near you, coloured by today's water temperature.