Why is a beetle with orange stripes in my house in winter?

Often an elm borer that emerged from elm firewood or lumber brought indoors.

Will it damage my furniture or house?

No; it does not re-infest wood, and it is harmless to people.

On this page

Adults are about 1/2 inch long with distinctive orangish markings and a fine coat of grayish hairs over most of the body.^[1][2]
It is a flat-faced longhorned beetle with long antennae.^[1]

Look-alike	How to tell them apart
Elm bark beetles	The elm borer can carry the Dutch elm disease fungus but is not its main vector; elm bark beetles are.^[1]

Found where American elm grows, including Missouri and Minnesota.^[1][2]

US map: public records from 38 states since 1990 (GBIF).

Larvae bore galleries under the bark of elm trees.^[1]

Adults are seen outdoors from May to August, but indoors they most often appear in winter.^[1][2]

In elms, larvae tunnel under the bark, and the beetle can carry the fungus that causes Dutch elm disease.^[1]
Indoors, beetles emerging from elm firewood or lumber leave cosmetic damage in that wood but do not re-infest it.^[2]

Harmless to people.^[2]

Indoors no wood treatment is called for: the beetle is harmless to people and does not re-infest the wood it emerged from.^[2]

Why is a beetle with orange stripes in my house in winter?: Often an elm borer that emerged from elm firewood or lumber brought indoors.^[2]
Will it damage my furniture or house?: No; it does not re-infest wood, and it is harmless to people.^[2]

Missouri Department of Conservation, “Elm Borer (Field Guide).” mdc.mo.gov/discover-nature/field-guide/elm-borer (accessed 2026-10-16)
University of Minnesota Extension (What insect is this?), “Elm borer.” apps.extension.umn.edu/garden/diagnose/insect/indoor/beetles/medium/elmborer.html (accessed 2026-10-16)
iNaturalist, “Saperda tridentata taxon page (order and family).” www.inaturalist.org/taxa/144007 (accessed 2026-10-06)

Updated 2026-10-16. Built from sourced records. Spot an error? Tell us.