Bug FAQSt. Lawrence Tiger Moth
Arctia parthenos · Order: Lepidoptera · Family: Erebidae
The St. Lawrence tiger moth has forewings about 28 to 33 mm long. It lives near streams and in mixed hardwood-conifer forests at mid to high elevations across boreal North America, from Alaska to Labrador and south to the Rocky and Appalachian Mountains. Caterpillars eat willow, alder and birch leaves, while adults fly from late May to early August each year.
Source: Wikipedia
How to recognize it
Arctia parthenos belongs to the moth family Erebidae.
Source: Wikipedia
Size
Forewing length ranges from 28 to 33 mm.
Source: Wikipedia
What it eats
Larvae feed on plants such as willow, alder and birch.
Source: Wikipedia
Life cycle
Adults are active from late May through early August, producing one generation each year.
Source: Wikipedia
When you see it
The flight period for adults spans late May to early August.
Source: Wikipedia
Where it comes from
It is native to boreal North America, from Alaska east to Labrador. Its range also extends southward in the Rocky Mountains to New Mexico and Arizona, and in the Appalachians to North Carolina.
Source: Wikipedia
Where it is found in the US
Recorded in 21 of 51 states and DC. Most records: Minnesota, Michigan, Montana, Maine, Colorado, Alaska, Wyoming, New Hampshire.
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 St. Lawrence tiger moths?
Adults are on the wing from late May until early August each year.
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 acreaDamages trees, gardens or cropsSources
- Wikipedia: https://en.wikipedia.org/wiki/Arctia_parthenos
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.