Bug FAQGranulate Ambrosia Beetle
Xylosandrus crassiusculus · Order: Coleoptera · Family: Curculionidae
Source: Wikipedia
The adult granulate ambrosia beetle is reddish-brown and about 2 to 3 mm long. Both adults and larvae feed on a cultivated fungus, Ambrosiella roeperi, that the female introduces into wood tunnels. Females mate with their brothers inside the galleries, stay with the brood over winter, and the larvae enlarge the tunnels as they grow.
Source: Wikipedia
How to recognize it
Adults are reddish-brown beetles.
Source: Wikipedia
Size
They measure roughly 2 to 3 mm in length.
Source: Wikipedia
Is it a pest in the house?
It attacks stacked timber, causing damage to stored wood. It usually targets stressed young trees and nursery stock, but can also attack apparently healthy young trees.
Source: Wikipedia
Where it lives
It commonly infests stacked timber, where it can cause economic damage.
Source: Wikipedia
What it eats
Adults and larvae eat only a symbiotic fungus they cultivate in wood galleries. The fungus involved is Ambrosiella roeperi.
Source: Wikipedia
Life cycle
The female remains with the brood, overwintering in the galleries while larvae expand them.
Source: Wikipedia
Where it comes from
It is native to Asia.
Source: Wikipedia
Where it is found in the US
Recorded in 28 of 51 states and DC. Most records: Kansas, Florida, Texas, Pennsylvania, Maryland, Georgia, North Carolina, Tennessee.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: introduced in Canada; introduced in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
How does this beetle damage wood?
The female bores tunnels in timber and introduces a fungus that both adults and larvae feed on, weakening the wood.
Source: Wikipedia
Where does the granulate ambrosia beetle come from?
It is native to Asia but has spread to many other continents.
Source: Wikipedia
Same family (Curculionidae)
Green Immigrant Leaf WeevilPolydrusus formosusDamages trees, gardens or crops
Black Vine WeevilOtiorhynchus sulcatusDamages trees, gardens or crops
Nettle weevilPhyllobius pomaceusDamages trees, gardens or crops
Asian Oak WeevilCyrtepistomus castaneusDamages trees, gardens or crops
Strawberry Root WeevilOtiorhynchus ovatusDamages trees, gardens or crops
Common Leaf WeevilPhyllobius pyriDamages trees, gardens or cropsSources
- Wikipedia: https://en.wikipedia.org/wiki/Xylosandrus_crassiusculus
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.