Bug FAQDicosmoecus gilvipes
Dicosmoecus gilvipes · Order: Trichoptera · Family: Limnephilidae
The October Caddis (Dicosmoecus gilvipes) is a caddisfly whose adults fly in autumn and is also called the Giant Orange Sedge. Larvae and nymphs are scraper-grazers that feed on periphyton growing on submerged rocks, and the final larval stage can reach up to 40 mm in length.
Source: Wikipedia
Size
The biggest larvae measure up to 40 mm in length.
Source: Wikipedia
Where it lives
It lives in streams at mid-elevations.
Source: Wikipedia
What it eats
Both larvae and nymphs scrape periphyton off submerged rocks.
Source: Wikipedia
Life cycle
The species has five larval instars in a single brood that appears once each mating season. The fifth instar is the largest, usually about 30 mm long and can reach up to 40 mm.
Source: Wikipedia
When you see it
Adults are most noticeable in autumn.
Source: Wikipedia
Where it comes from
In North America it occurs from northern California and Colorado up to British Columbia and east to Nevada, Idaho, Montana and Alberta.
Source: Wikipedia
Where it is found in the US
Recorded in 6 of 51 states and DC. Most records: California, Washington, Oregon, Idaho, Alaska, Montana.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada; native in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
When are October Caddis adults active?
Adults are most active and can be seen flying in autumn.
Source: Wikipedia
What do the larvae eat?
Larvae and nymphs graze on periphyton that grows on submerged rocks in streams.
Source: Wikipedia
How big do the larvae get?
The final larval stage can grow up to about 40 mm long, with most individuals around 30 mm.
Source: Wikipedia
Same family (Limnephilidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Dicosmoecus_gilvipes
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-26 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-26.