The short answer
- Chile has 214 described caddis species in 18 families, with a high degree of endemism.
- In January samples from the rivers we fish, the most common caddis were Dolophilodes and the net-spinning Smicridea.
- Caddis were 21% of the prey items of adult brown trout in the Palena River, second only to snails.
- Patagonian caddis emerge in spring and summer; guides in Aysén report the best hatches in December and January.
- Guides match the adults with the X-Caddis in sizes 14–16 and the Streaking Caddis in 12–14.
Which caddis live in Coyhaique's rivers?
Chile's national catalogue lists 214 caddis species in 18 families, with a high degree of endemism. The most diverse family is Hydrobiosidae, with 20 genera, 47 species and the highest share of species found only in Chile. Limnephilidae, with 27 large and abundant species, is the most characteristic caddis of the streams that run through Patagonia's southern beech forests, and the Gondwanan family Helicophidae counts 5 genera and 15 species.
The Aysén River basin survey of January 2006 found 10 caddis taxa. In four rivers we fish:
| River | Caddis larvae per m² | Most numerous |
|---|---|---|
| Emperador Guillermo | 68 | Dolophilodes (30) |
| Ñirehuao | 67 | Dolophilodes (58) |
| Mañihuales | 60 | Dolophilodes (40) |
| Simpson | 20 | Smicridea (18) |
Larvae per square meter (about 11 square feet) in riffle samples, January 2006. One survey and one visit per river. Source: Oyanedel et al. (2008), table II.
The net-spinning Smicridea also turned up in the Emperador Guillermo (25 per square meter, counting both subgenera), the Mañihuales (10) and the Ñirehuao (3). The same samples held Hydrobiosidae in the Mañihuales and the Ñirehuao, Hudsonema in the Ñirehuao, and Mastigoptila and Helicopsyche in the Emperador Guillermo.
Why do caddis feed trout at every stage?
Caddisflies go through complete metamorphosis: a larva that lives on the bottom for most of its life, a pupa that rises to the surface to hatch and a winged adult. The families in our rivers make a living in different ways. Smicridea and Dolophilodes spin silk nets to strain food from the current; hydrobiosid larvae roam the stones without a case; Helicopsyche builds a tiny case shaped like a snail shell; limnephilids carry portable cases. A larva swept off a stone, a pupa on its way up and an adult skittering on the surface are three different meals for a trout.
When do caddis hatch?
In a mountain stream of the Patagonian Andes in Argentina, four of five caddis species studied completed one generation a year, with adult emergence relatively well synchronized in spring and summer. Water temperature, flow and the amount of organic detritus were the main drivers of the caddis community there.
Guides who fish the Aysén Region place the best caddis hatches in December and January. Summer evenings are classic caddis time around Coyhaique, as our guide to Coyhaique's rivers describes, and in midsummer the evening rise can run until about 10 pm.
How much do trout eat caddis?
In the Palena River, in northern Chilean Patagonia, caddis were 21% of the prey items of adult brown trout, second only to snails at 25%, and 13% for adult rainbows. Juvenile rainbows ate even more: 23% of their prey items, more than any other group. The full menu, crabs and snails included, is in what trout eat in Chilean Patagonia.
Which flies match them?
Flies are included in both of our programs; this is the caddis logic. For the adults, guides in Aysén fish the X-Caddis in sizes 14 to 16 and the Streaking Caddis in 12 to 14. For larvae and pupae, a small beadhead nymph fished through the riffles. The rest of the riverbed has its own notes: mayflies and stoneflies.
Sources
- Rojas, F. (2006). Estado de conocimiento de los Trichoptera de Chile [Current state of knowledge of Trichoptera of Chile]. Gayana 70(1): 65–71. Read the source
- Oyanedel, A., Valdovinos, C., Azócar, M., Moya, C., Mancilla, G., Pedreros, P. & Figueroa, R. (2008). Spatial distribution patterns of benthic macroinvertebrates in the Aysén River basin (Chilean Patagonia). Gayana 72(2): 241–257. Read the source
- Brand, C. & Miserendino, M.L. (2011). Life history strategies and production of caddisflies in a perennial headwater stream in Patagonia. Hydrobiologia 673: 137–151. Read the source
- Bravo, S., Whelan, K. & Silva, M.T. (2021). Assessment of trout populations inhabiting the Palena River, southern Chile. Latin American Journal of Aquatic Research 49(1): 29–39. Read the source
- Heinonen, T. Matching the hatch in Aysén, Patagonia. Kalakamu field guide (a guide's field observations, not a scientific study). Read the source
