Bug FAQMilbert's Tortoiseshell
Aglais milberti · Order: Lepidoptera · Family: Nymphalidae
Milbert's tortoiseshell is a medium-sized butterfly with a wingspan of about 4 to 6 cm. Its upper wings are black with wide orange bands that fade to yellow near the inner edge, narrow black borders, and sometimes blue spots on the hindwing.
Source: Wikipedia
How to recognize it
Both wings have narrow black margins and the hindwing may show blue spots.
Source: Wikipedia
Size
Wingspan ranges from 4.2 to 6.3 cm.
Source: Wikipedia
Where it lives
Found in wet areas like moist pastures, marshes, trails and roadsides.
Source: Wikipedia
Life cycle
Produces two broods from May through October. Adults hibernate, often gathering in small groups.
Source: Wikipedia
When you see it
Two broods appear between May and October.
Source: Wikipedia
Lookalikes
One of only two tortoiseshell butterflies in North America. The other is the California tortoiseshell, Nymphalis californica.
Source: Wikipedia
Where it is found in the US
Recorded in 40 of 51 states and DC. Most records: Vermont, Colorado, Alaska, Idaho, Washington, California, Wyoming, Montana.
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
Questions people ask
What habitats should I look for them in?
They are common in wet places such as moist pastures, marshes, trails and roadsides.
Source: Wikipedia
When are they active during the year?
Adults appear in two generations from May through October.
Source: Wikipedia
How can I tell this butterfly apart from similar species?
It has black upper wings with wide orange bands that fade to yellow, narrow black borders, and may have blue spots on the hindwing; the only similar North American tortoiseshell is the California tortoiseshell.
Source: Wikipedia
Same family (Nymphalidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Aglais_milberti
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-22 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.