Bug FAQBrown Tree Ant
Lasius brunneus · Order: Hymenoptera · Family: Formicidae
Also called: Brown Ant
Queens are small, uniformly dark brown and have a slim, flat shape. Workers show two colors and can be mistaken for Lasius emarginatus. In England they nest mainly in oak trees or rotting wood, but also appear under stones and on the ground. The species ranges across Europe from Sweden down to Anatolia. Mated queens take wing in warm May mornings, usually from early morning to early afternoon.
Source: Wikipedia
How to recognize it
Workers are bicolored and can be confused with Lasius emarginatus.
Source: Wikipedia
Size
Queens are smaller than other Lasius species and are uniformly dark brown with a slim, flat appearance.
Source: Wikipedia
Life cycle
Nuptial flights occur as early as May on warm days, typically from early morning to early afternoon.
Source: Wikipedia
When you see it
Nuptial flights are recorded in May on warm mornings and afternoons.
Source: Wikipedia
Lookalikes
They may be mistaken for Lasius emarginatus.
Source: Wikipedia
Where it is found in the US
Recorded in 1 of 51 states and DC. Most records: Oklahoma.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
More photos
Questions people ask
When do brown tree ants have their nuptial flights?
They fly in warm May mornings, usually from early morning to early afternoon.
Source: Wikipedia
Where are brown tree ants most likely to nest in England?
They typically nest in oak trees or rotting wood, but can also be found under stones and on the ground.
Source: Wikipedia
How can I tell a brown tree ant worker from other ants?
Workers are bicolored and can be confused with Lasius emarginatus.
Source: Wikipedia
Same family (Formicidae)
Eastern Black Carpenter AntCamponotus pennsylvanicusCan damage your home
Red Imported Fire AntSolenopsis invictaCan sting
American Winter AntPrenolepis imparis
Argentine AntLinepithema humileNuisance, not dangerous
Immigrant Pavement AntTetramorium immigransCan sting
Odorous House AntTapinoma sessileCan damage your homeSources
- Wikipedia: https://en.wikipedia.org/wiki/Lasius_brunneus
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 2026-10-22.