Bug FAQSemirelict Underwing Moth
Catocala semirelicta · Order: Lepidoptera · Family: Erebidae
Also called: Semirelict Underwing
The semirelict underwing is a moth in the Erebidae family. Its forewings are roughly 30 mm long and the wingspan is between 65 and 75 mm. Caterpillars feed on balsam poplar, quaking aspen and various willows.
Source: Wikipedia
How to recognize it
Catocala semirelicta belongs to the moth family Erebidae.
Source: Wikipedia
Size
Forewing length is about 30 mm; the full wingspan measures 65 to 75 mm.
Source: Wikipedia
Where it lives
It lives in parts of the United States such as Nevada, Colorado, Utah, California and Maine, and also across Canada to British Columbia.
Source: Wikipedia
What it eats
The larvae eat the leaves of balsam poplar, quaking aspen and willow species.
Source: Wikipedia
Life cycle
There is likely one generation each year.
Source: Wikipedia
When you see it
Adults are on the wing from July through September, depending on location.
Source: Wikipedia
Where it comes from
Its native range covers North America from the western states and provinces to the eastern seaboard.
Source: Wikipedia
Where it is found in the US
Recorded in 25 of 51 states and DC. Most records: Wyoming, Colorado, Utah, Montana, Michigan, California, Idaho, Oregon.
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 can I see adult semirelict underwings?
Adults fly from July to September, with timing varying by region.
Source: Wikipedia
What do the caterpillars eat?
Caterpillars feed on balsam poplar, quaking aspen and willow plants.
Source: Wikipedia
How big is this moth?
Its forewings are about 30 mm long and the wingspan ranges from 65 to 75 mm.
Source: Wikipedia
Where is the semirelict underwing found?
It occurs in western and some eastern U.S. states and across Canada to British Columbia.
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 acreaSources
- Wikipedia: https://en.wikipedia.org/wiki/Catocala_semirelicta
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-23 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-23.