Bug FAQForbes' Sallow
Sympistis forbesi · Order: Lepidoptera · Family: Noctuidae
Forbes' Sallow is a moth with green forewings that have a reddish back. Adults fly in late summer and there is one generation each year. The larvae eat Triosteum plants such as T. perfoliatum.
Source: Wikipedia
How to recognize it
The moth’s forewings are green with a reddish dorsum.
Source: Wikipedia
Size
Forewing length is about 14.5 to 16 mm in males and 14 to 16.5 mm in females.
Source: Wikipedia
Where it lives
It has been recorded in Iowa, Illinois and Minnesota.
Source: Wikipedia
What it eats
Larvae feed on species of the plant genus Triosteum, including T. perfoliatum and possibly T. aurantiacum.
Source: Wikipedia
Life cycle
Adults are on the wing in late summer, producing one generation per year.
Source: Wikipedia
When you see it
Adults appear in late summer.
Source: Wikipedia
Where it comes from
It is known from those three Midwestern states and is thought to have disappeared from New York and New Jersey.
Source: Wikipedia
Where it is found in the US
Recorded in 4 of 51 states and DC. Most records: Wisconsin, Illinois, Iowa, Minnesota.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
When can I see adult Forbes' Sallow?
Adults are active in late summer, with one generation each year.
Source: Wikipedia
What do the caterpillars eat?
The larvae feed on Triosteum plants such as Triosteum perfoliatum.
Source: Wikipedia
Same family (Noctuidae)
Ipsilon Dart MothAgrotis ipsilonDamages trees, gardens or crops
Fall Armyworm MothSpodoptera frugiperdaDamages trees, gardens or crops
Army Cutworm MothEuxoa auxiliarisDamages trees, gardens or crops
Large Yellow UnderwingNoctua pronubaDamages trees, gardens or crops
Silver ΥAutographa gamma
American DaggerAcronicta americanaCan irritate skinSources
- Wikipedia: https://en.wikipedia.org/wiki/Sympistis_forbesi
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-28 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-28.