Stenopsyche marmorata
In 3 days ~10% in a week ~20%
Stenopsyche marmorata is a species of caddisfly found in Japan. The larvae live in fast-flowing streams and are harvested by Japanese fishermen for zazamushi, a traditional dish made from a mixture of aquatic insect larvae cooked in soya sauce and sugar. This species is widely distributed in Japan, Sakhalin (Russia), the Korean Peninsula, northeastern China, and the Russian Primorsky Territory.
The larvae spin silk nets in streams in which animal and plant matter are trapped and upon which they feed. The larvae grow longer than 2 cm and are the largest caddisflies in the region. In the Primorsky Krai, they constitute 77% of all the trichopteran biomass and 35% of all riverine benthic biomass. The larvae live amid mussels which they use to anchor their filter nets in the Primorsky region. In Japan they are used for monitoring pollutants.
The genus Stenopsyche has more than 90 species mainly found in the eastern Palearctic (a few in the Oriental and African region as well). In the Tenryu-gawa River Community in Nagano, licenses are given out for their harvest. Zazamushi is predominantly composed of the larvae of Stenopsyche marmorata. They were originally used and eaten locally until around 1956 when they were packaged and sold as a souvenir by the company Kaneman. The aquatic silk has been a subject of study. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Tokyo | 🇯🇵 Japan |
Rare
Under 5% of wildlife watchers report a Stenopsyche marmorata sighting in Tokyo on a given day, based on 8 verified sightings from GBIF citizen-science data. It is the 872nd most-seen of the 1013 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
Any time of year
In every month with enough records, under 5% of wildlife watchers report a Stenopsyche marmorata in Tokyo on a given day, so our monthly data shows no clear season.
Only Tokyo, in our data
Tokyo is the only city on Wallace's Line with enough records to rate Stenopsyche marmorata sightings: under 5% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Stenopsyche marmorata is recorded against all the insects logged in Tokyo (8 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
