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Sowbug (Asellus spp.)
Crustacean, in the drift all year, active in water between 33 and 70°F, and imitated at #14–18. Recorded from the Virginia mountains, where 796 Virginia rivers on this site carry a page.
An aquatic isopod rather than an insect: grey, flat-backed and many-legged, slower and more sluggish than a scud, and common in spring creeks, limestone water and tailwaters. It is in the water every month of the year, so there is no season to wait for and no emergence to time. It crawls rather than swims, which decides how it is fished. A grey sowbug pattern dead-drifted on the bottom, often under an indicator in winter, is a year-round fly on the water that holds them. The active band is broad, 33 to 70 degrees, spanning cold, cold-transitional, cool and warm water, and hooks run 14 to 18. Flatter and greyer than a scud, and found in the same limestone water, it is easily mistaken for one. A Sowbug 14 to 18 is the direct imitation; a Grey Scud or Walt's Worm 12 to 18, a Pheasant Tail 12 to 22, or a Hare's Ear 10 to 18 all stand in.
- #14–18Hook size
- 33–70°FWater, active
- all yearAvailable
- 1Life stage fished
What it is
Crustacean · Asellus spp. · adult
An aquatic isopod: grey, flat-backed, many-legged, slower and more sluggish than a scud. Common in spring creeks, limestone water and tailwaters.
Flatter and greyer than a scud, and in the same limestone water. A dead-drift under an indicator in winter.
When it hatches
In the water twelve months a year, which is why the panel in the app ranks it below anything with a season.
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.
Active from 33°F to 70°F. On this map that is cold, cold-transitional, cool, warm water — the band crosses 3 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.
| Stage | What it is |
|---|---|
| adult | Crawls rather than swims. A grey sowbug pattern dead-drifted on the bottom is a year-round fly on the water that holds them. |
Matching flies
6 patterns in this book imitate the Sowbug, 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.
- Hare's Ear Nymph nymph · #10–18 — Looks like everything and nothing. The other half of a two-nymph rig.
- Pheasant Tail Nymph nymph · #12–22 — The mayfly nymph. Beadhead or not, size 16, and half the trout in the world have eaten one.
- Ray Charles nymph · #14–18 — A grey shellback sowbug with no legs and no tail. Named because it is tied blind-simple, and it outfishes elaborate sowbugs everywhere they both swim.
- Grey Scud nymph · #12–18 — The living colour. Weedy, watercress-lined spring creeks, every month.
- Sowbug nymph · #14–18 — Flat, grey, unglamorous, and the main food item in limestone water.
- Walt's Worm nymph · #12–18 — Dubbing on a hook. Suggests cranefly larvae, sowbugs and everything else pale and wriggling.
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.
- Smith River the Virginia mountains · July mean 51.9°F
- Back Creek the Virginia mountains · July mean 49.9°F
- Big Cherry Creek the Virginia mountains · July mean 49.9°F
- Big Ivy Creek the Virginia mountains · July mean 49.9°F
- Boothe Creek the Virginia mountains · July mean 49.9°F
- Brogan Branch the Virginia mountains · July mean 49.9°F
- Browns Dan River the Virginia mountains · July mean 49.9°F
- Brushy Fork the Virginia mountains · July mean 49.9°F
- Camp Creek the Virginia mountains · July mean 49.9°F
- Conners Creek the Virginia mountains · July mean 49.9°F
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.
- the Wisconsin driftless WI
- southern lower Michigan MI
- the Virginia mountains VA
Rivers in these regions with a page here
- Jackson River
- Smith River
- Als Run
- Alum Creek
- Amos Branch
- Anderson Run
- Ararat River
- Auberry Creek
- Back Creek
- Back Creek
- Back Fork
- Back Run
- Baker Branch
- Baldwin Branch
- Baldwin Branch
- Barbours Creek
- Bark Camp Branch
- Bark Camp Branch
- Barkcamp Branch
- Barnard Creek
- Barney Run
- Barterbrook Branch
- Batie Creek
- Battery Creek
- and 772 more
Related hatches
Same family, or overlapping this one's calendar on the same water.
- Crayfish Orconectes spp. · Crustacean · May–October
- Scud Gammarus spp. · Crustacean · all year
- Black Ant Formicidae · Terrestrial · June–September
- Blackfly Simulium spp. · Midge · April–June
- Blue-Winged Olive Baetis spp. · Mayfly · March–May and September–November