Bug FAQWestern Underwing Moth
Catocala californica · Order: Lepidoptera · Family: Erebidae
The Western Underwing Moth has a wingspan of about 65 mm. Caterpillars feed on black walnut and willow species. Adults fly from June to August, depending on location.
Source: Wikipedia
Size
The wingspan is about 65 mm.
Source: Wikipedia
What it eats
The larvae feed on black walnut (Juglans nigra) and various willow (Salix) species.
Source: Wikipedia
Life cycle
Adults are on the wing from June to August, with timing varying by location.
Source: Wikipedia
When you see it
Adults are active during the summer months, typically June through August.
Source: Wikipedia
Where it is found in the US
Recorded in 19 of 51 states and DC. Most records: Colorado, California, Wyoming, Utah, Idaho, Montana, New Mexico, Washington.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in United States; native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
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_californica
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.