Bug FAQJoined Underwing Moth
Catocala junctura · Order: Lepidoptera · Family: Erebidae
Also called: Joined Underwing
The Joined Underwing moth has a wingspan of about 70 to 75 mm or larger and its forewings are gray-brown with distinct black bands above and a whitish underside. Its hindwings are orange-red with two concentric blackish bands and lack hairs at the base. It lives near water where willow and Fremont cottonwood grow, flies from June to September, and is found across much of temperate North America.
Source: Wikipedia
Size
Wingspan ranges from 70 to 75 mm or more.
Source: Wikipedia
Where it lives
Typically found near water where its larval food plants grow abundantly.
Source: Wikipedia
What it eats
Caterpillars feed on willow species and, in the western part of the range, on Fremont cottonwood.
Source: Wikipedia
Life cycle
Adults are on the wing from June through September, depending on location. There is probably one generation per year.
Source: Wikipedia
When you see it
Adults are active from June to September, varying with region.
Source: Wikipedia
Where it comes from
Occurs throughout temperate North America, from the northeastern US west to Montana, Colorado, Oklahoma, Arizona, Texas, and north into southern Alberta and Saskatchewan. Also recorded west of the Rockies in California and southeastern British Columbia.
Source: Wikipedia
Lookalikes
The name Catocala aspasia was formerly applied to this species but actually refers to the similar C. electilis. Many former species or subspecies have been merged into C. junctura; the vernacular name "Stretch's underwing" refers to the former C. stretchii.
Source: Wikipedia
Where it is found in the US
Recorded in 28 of 51 states and DC. Most records: Colorado, California, Utah, South Dakota, Arizona, New Mexico, Illinois, Ohio.
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 Joined Underwing moths active?
Adults fly from June to September, with exact timing depending on the region.
Source: Wikipedia
What do the caterpillars eat?
They feed on willow species and, in the western part of their range, on Fremont cottonwood.
Source: Wikipedia
Where can I find this moth?
It lives near water across much of temperate North America, from the northeastern US west to the Rockies and north into southern Canada.
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_junctura
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.