Bug FAQGrote's Underwing Moth
Catocala grotiana · Order: Lepidoptera · Family: Erebidae
Grote's underwing moth has a wingspan of about 70 to 80 mm. Adults fly in late summer, typically from August through September depending on where they live. It occurs in the western United States, from Arizona north through Utah and Colorado, and has also been recorded in Washington and areas east of California.
Source: Wikipedia
How to recognize it
Catocala grotiana, known as Grote's underwing, belongs to the moth family Erebidae.
Source: Wikipedia
Size
The species measures 70 to 80 mm across the wings when spread.
Source: Wikipedia
Where it lives
It is found in the United States from Arizona north through Utah into Colorado.
Source: Wikipedia
What it eats
The caterpillars feed on species of poplar and willow (Populus and Salix).
Source: Wikipedia
Life cycle
There is probably one generation each year.
Source: Wikipedia
When you see it
Adults are on the wing from August to September, varying with location.
Source: Wikipedia
Where it comes from
Grote's underwing is native to the United States, ranging from Arizona up through Utah and Colorado. Its range extends to Washington and other western areas north and east of California.
Source: Wikipedia
Where it is found in the US
Recorded in 13 of 51 states and DC. Most records: Colorado, Wyoming, Arizona, New Mexico, Utah, Idaho, Montana, Nevada.
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 Grote's underwing moths active?
Adults are typically seen flying from August through September, though the exact timing depends on the region.
Source: Wikipedia
What do the larvae eat?
The caterpillars feed on poplar (Populus) and willow (Salix) species.
Source: Wikipedia
How many generations do they have each year?
They probably produce one generation per year.
Source: Wikipedia
Same family (Erebidae)
Spongy MothLymantria disparDamages trees, gardens or crops
Fall Webworm MothHyphantria cuneaDamages trees, gardens or crops
Brown-tail MothEuproctis chrysorrhoeaCan irritate skin
Isabella Tiger MothPyrrharctia isabella
Virginian Tiger MothSpilosoma virginicaCan irritate skin
Salt Marsh MothEstigmene acreaDamages trees, gardens or cropsSources
- Wikipedia: https://en.wikipedia.org/wiki/Catocala_grotiana
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-24.