Bug FAQMournful Duskywing
Erynnis tristis · Order: Lepidoptera · Family: Hesperiidae
The Mournful Duskywing is a small brown skipper with a white fringe on the hindwing. Adults measure about 28 to 31 mm in wingspan and are slightly smaller than the similar Erynnis funeralis. It lives in forest clearings, oak woodlands, and also in urban areas across California and into northern Baja California.
Source: Wikipedia
How to recognize it
The butterfly is mottled brown with a distinctive white fringe on the hindwing.
Source: Wikipedia
Size
Adults are 28 to 31 mm long, smaller than the related Erynnis funeralis which is 33 to 38 mm.
Source: Wikipedia
Where it lives
It prefers forest clearings and oak woodlands. It also occurs in urban settings, showing flexibility to human disturbance.
Source: Wikipedia
What it eats
Caterpillars feed on oak leaves, while adults sip nectar from various flowers and puddle for minerals.
Source: Wikipedia
Life cycle
Females lay spherical eggs on the tip of the host plant.
Source: Wikipedia
When you see it
The species has multiple generations per year and shows no distinct seasonal forms.
Source: Wikipedia
Where it comes from
It is found throughout California and extends into northern Baja California.
Source: Wikipedia
Lookalikes
It is often confused with Erynnis funeralis because both have a white hindwing fringe.
Source: Wikipedia
Where it is found in the US
Recorded in 9 of 51 states and DC. Most records: California, Texas, Arizona, New Mexico, Kansas, Colorado, Oklahoma, Oregon.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
How can I tell the Mournful Duskywing apart from similar species?
Look for the mottled brown wings with a white fringe; the similar Erynnis funeralis also has a white fringe, so size differences (28 to 31 mm vs 33 to 38 mm) help separate them.
Source: Wikipedia
Where is this butterfly found?
It lives in forest clearings, oak woodlands, and urban areas across California into northern Baja California.
Source: Wikipedia
Same family (Hesperiidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Erynnis_tristis
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.