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Little Sister Caddis (Cheumatopsyche spp.)

Caddis, hatching June–August, active in water between 60 and 74°F, and imitated at #16–20. Recorded from northern lower Michigan, southern lower Michigan and the Upper Peninsula, where 1140 Michigan rivers on this site carry a page.

Little Sister Caddis, Cheumatopsyche spp.
Common netspinner, genus Cheumatopsyche (7903539270) — Bob Henricks from Charlottesville, United States, CC BY-SA 2.0, via Wikimedia Commons.
Subbasins with trout water where it is on record: 42 of Michigan's 59.
See Michigan's trout water on the live map → Every reach coloured by water temperature — the water these hatches come off.

What it is

Caddis · Cheumatopsyche spp. · larva → pupa → adult

A small tan-to-ginger caddis with mottled wings, close to the spotted caddis in shape and two or three sizes smaller. Cream-to-olive net-spinning larva.

The smaller relative of the spotted caddis, and probably the most numerous adult caddis on summer water in all these states. Rarely announced as a hatch because it is never absent.

When it hatches

Peak is June–August. 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.

60°F 74°F

Active from 60°F to 74°F. On this map that is cold-transitional, cool, warm water — the band crosses 2 of the three breaks 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.

StageWhat it is
larva A net-spinner in riffles, tethered in a silk retreat and dislodged constantly. A green or tan caddis larva in fast water is fishing this.
pupa Rises to emerge from late morning through evening in summer. A sparkle pupa in the surface film is the reliable answer.
adult On the water through summer in numbers that never quite become an event. Egg-laying females dive and swim, which is why a swung wet fly works when a drifted dry does not.

Matching flies

5 patterns in this book imitate the Little Sister 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.

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.