BirdTrout
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Caterpillar (Lepidoptera larvae)
Terrestrial, hatching May–September, active in water between 55 and 75°F, and imitated at #8–14. Recorded from 7 of the 8 regions this map covers, across Michigan, Wisconsin, Virginia and North Carolina.
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- #8–14Hook size
- 55–75°FWater, active
- May–SepPeak months
- 1Life stage fished
What it is
Terrestrial · Lepidoptera larvae · larva
Larval moths and butterflies — tent caterpillars, woolly bears, spongy moth larvae — fuzzy or smooth, an inch or more long, and heavy for their size.
Tent caterpillars, woolly bears and spongy-moth larvae, all of which fall off overhanging hardwood in quantity. Distinct from the inchworm only in size and in that they sink; a caterpillar that has been in the water a minute is fished under the surface, not on it.
When it hatches
Peak is May–September. 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.
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 55°F to 75°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 |
|---|---|
| larva | Falls off overhanging hardwood through the summer, in real numbers in a defoliation year. Unlike an inchworm it sinks quickly, so a caterpillar that has been in the water a minute is fished under the surface rather than on it. |
Matching flies
4 patterns in this book imitate the Caterpillar, 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.
- Black Foam Ant terrestrial · #14–20 — Floats low, which is how a real ant sits. Small water, tight to the bank.
- Foam Inchworm terrestrial · #12–16 — A length of bright green foam and nothing else. Cast tight to overhanging hardwood; the natural arrives from above, not from upstream.
- Green Weenie nymph · #12–16 — Chartreuse chenille. Appalachian brook-trout water does not have a better fly in June.
- Woolly Worm terrestrial · #8–14 — Chenille body palmered with hackle. Older than most of the flies it sits next to, and still the caterpillar pattern.
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.
- Augusta Creek southern lower Michigan · July mean 65.0°F
- Dickinson Creek southern lower Michigan · July mean 65.0°F
- High Bank Creek southern lower Michigan · July mean 65.0°F
- Minges Brook southern lower Michigan · July mean 65.0°F
- North Branch Rice Creek southern lower Michigan · July mean 65.0°F
- Portage Creek southern lower Michigan · July mean 65.0°F
- Rice Creek southern lower Michigan · July mean 65.0°F
- Badfish Creek northern Wisconsin · July mean 65.1°F
- East Fork Raccoon Creek northern Wisconsin · July mean 65.1°F
- Rutland Branch northern Wisconsin · July mean 65.1°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.
- northern lower Michigan MI
- southern lower Michigan MI
- the Upper Peninsula MI
- the Wisconsin driftless WI
- northern Wisconsin WI
- the Virginia mountains VA
- the North Carolina mountains NC
Rivers in these regions with a page here
- Au Sable River
- Catawba River
- Jackson River
- Muskegon River
- Escanaba River
- Saint Croix River
- Smith River
- Tygart Valley River
- Kalamazoo River
- Aaron Creek
- Aaron Run
- Aarons Run
- Abb Run
- Abes Run
- Abitosse Creek
- Abram Creek
- Acme Creek
- Acorn Branch
- Adamcamp Branch
- Adams Creek
- Adams Creek
- Adamson Run
- Addis Creek
- Adkins Rockhouse Branch
- and 6371 more
Related hatches
Same family, or overlapping this one's calendar on the same water.
- Black Ant Formicidae · Terrestrial · June–September
- Grasshopper Acrididae · Terrestrial · July–September
- Leafhopper Cicadellidae · Terrestrial · June–September
- Annual Cicada Neotibicen spp. · Terrestrial · July–August
- Cinnamon Flying Ant Formicidae (alate) · Terrestrial · August–September