Biston robustum
In 3 days ~10% in a week ~20%
Biston robustum is a species of moth belonging to the family Geometridae. This is a large moth and has the English common name in its native range as the giant geometer moth (The Japanese name is トビモンオオエダシャク, Korean name 몸큰가지나, Chinese 褐纹大尺蛾). It is related, and generally similar, to the widespread Peppered Moth.
The species is found in China (Shandong, Shaanxi, Shanghai, Jiangsu, Jiangxi), Taiwan, Japan, Russia, North Korea, South Korea and Vietnam. This species has recently gained attention due to the discovery of its use of chemical mimicry to avoid predation by ants. The larva of this species, in common with many other geometrids, uses visual mimicry, strongly resembling a twig of its host plant. Recent studies have shown that it also uses chemical mimicry, storing chemicals from its food in its cuticle so that ants are largely unable to distinguish it from a twig, even after making contact with their highly sensitive antennae. Ants foraging for prey have been observed walking along the moth larvae, oblivious of their presence. Utilizing the chemicals directly from diet is advantageous as the larva will always be a chemical match to the plant it is actually feeding on (the species is highly polyphagous - see below). It has been predicted that, with further study, other species will also be shown use this form of defence. 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 Biston robustum sighting in Tokyo on a given day, based on 13 verified sightings from GBIF citizen-science data. It is the 585th 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.
March
In that month about 10% of wildlife watchers report a Biston robustum in Tokyo on a given day, against under 5% in April to February, the lowest months.
Only Tokyo, in our data
Tokyo is the only city on Wallace's Line with enough records to rate Biston robustum sightings: under 5% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Biston robustum is recorded against all the insects logged in Tokyo (13 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.
