Bug FAQOak Besma Moth
Besma quercivoraria · Order: Lepidoptera · Family: Geometridae
Also called: Oak Besma
The oak besma moth has a wingspan of about 27 to 41 mm. Adults look different between males and females. It lives across southern Canada and most of the United States, except California. Caterpillars eat oak, elm, poplar, willow, white spruce and especially paper birch leaves in southern Canada. There are two generations each year, with adults flying from spring into early fall depending on the region.
Source: Wikipedia
How to recognize it
Males and females have different appearances.
Source: Wikipedia
Size
Wingspan ranges from 27 mm to 41 mm.
Source: Wikipedia
Where it lives
Found throughout southern Canada and the United States, except California.
Source: Wikipedia
What it eats
Larvae feed on oak, elm, poplar, willow, white spruce, and mainly paper birch leaves in southern Canada.
Source: Wikipedia
Life cycle
Produces two generations per year.
Source: Wikipedia
When you see it
Adults are on the wing April-September in the south, May-August in Ontario, and late May-July in Alberta.
Source: Wikipedia
Where it comes from
Native to southern Canada and most of the United States, excluding California.
Source: Wikipedia
Where it is found in the US
Recorded in 42 of 51 states and DC. Most records: Massachusetts, Virginia, Michigan, North Carolina, Connecticut, Alabama, Maryland, Pennsylvania.
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 oak besma moth adults active?
Adults fly from April to September in the southern U.S., May to August in Ontario, and late May to July in Alberta.
Source: Wikipedia
How many generations does the oak besma moth have each year?
There are two generations per year.
Source: Wikipedia
Same family (Geometridae)
Willow BeautyPeribatodes rhomboidaria
Pale BeautyCampaea perlataDamages trees, gardens or crops
Large Lace-border MothScopula limboundataDamages trees, gardens or crops
Riband WaveIdaea aversata
Yellow Shell MothCamptogramma bilineata
Large Maple Spanworm MothProchoerodes lineolaDamages trees, gardens or cropsSources
- Wikipedia: https://en.wikipedia.org/wiki/Besma_quercivoraria
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.