Spodoptera exigua
In 3 days ~40% in a week ~60%
The beet armyworm or small mottled willow moth (Spodoptera exigua) is one of the best-known agricultural pest insects. It is also known as the asparagus fern caterpillar. It is native to Asia, but has been introduced worldwide and is now found almost anywhere its many host crops are grown. The voracious larvae are the main culprits. In the British Isles, where it is an introduced species and not known to breed, the adult moth is known as the small mottled willow moth.
Thought to have originated in south-east Asian countries, it was first discovered in North America about 1876, when it was found in Oregon, and it reached Florida in 1924. The adult is a drab brown or grey moth with a wingspan of 26–32 millimetres (1–1+1⁄4 in). Forewing is greyish ochreous in color, washed with dull yellow and sprinkled with black scales. Inner and outer lines are double, indistinct, filled in with pale yellowish color. A dark waved median shade visible before lower half of outer line. Cell is dark brown. Orbicular stigma is pale or bright yellow, and round, whereas reniform has a curved brown lunule in centre. The submarginal line is pale grey. There is the darker shade... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Death Valley National Park | 🇺🇸 United States | |
| 2 | Sierra Nevada National Park | 🇪🇸 Spain | |
| 3 | Doñana National Park | 🇪🇸 Spain | |
| 4 | Joshua Tree National Park | 🇺🇸 United States | |
| 5 | Pyrénées National Park | 🇫🇷 France |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Porto | 🇵🇹 Portugal | |
| 2 | Valencia | 🇪🇸 Spain | |
| 3 | Madrid | 🇪🇸 Spain | |
| 4 | London | 🇬🇧 United Kingdom | |
| 5 | Liverpool | 🇬🇧 United Kingdom | |
| 6 | Barcelona | 🇪🇸 Spain | |
| 7 | Austin | 🇺🇸 United States | |
| 8 | Birmingham | 🇬🇧 United Kingdom | |
| 9 | San Diego | 🇺🇸 United States | |
| 10 | Lisbon | 🇵🇹 Portugal |
With luck
About 10% of wildlife watchers report a Beet Armyworm Moth sighting in Sierra Nevada National Park on a given day, based on 16 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 147th most-seen of the 479 insects we can rate there. Over three days the chance rises to about 40%, and over a week to about 60%, if each day is a fresh chance.
September
In that month about 30% of wildlife watchers report a Beet Armyworm Moth in Sierra Nevada National Park on a given day, against under 5% in May, October and December–March, the lowest months.
Between 8 and 11 pm
Across all the parks we cover, that three-hour window holds the most Beet Armyworm Moth sightings with a recorded time, and about 6 in 10 of them come between 6 pm and 6 am: it is seen both by day and at night.
Among the best
Of the 5 parks where we can rate Beet Armyworm Moth sightings, Sierra Nevada National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Death Valley National Park (United States, about 10%).
Same family: Noctuidae
The closest relatives of the Beet Armyworm Moth that you can see in Sierra Nevada National Park (family Noctuidae, Cutworm Moths and Allies) are Turnip Moth (about 20%), The Bordered Straw (about 20%) and Silver Υ (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Beet Armyworm Moth is recorded against all the insects logged in Sierra Nevada National Park (16 verified sightings from 2019 to 2026), 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.
