Clubiona robusta
Stout Sac Spider Identification in Australia
A small Clubiona hunter associated with bark and silk retreats. Its resting sac is shelter, rather than a prey-catching web.
Usually low risk; avoid handlingAbout Stout sac spider
Clubiona robusta is the stout sac spider, a member of Clubionidae. Work in South Australia documented it beneath eucalyptus bark, where females build substantial silk nests. These shelters can be used for overwintering, mating and guarding eggs. Juveniles also make moulting chambers. A silk sac under bark therefore tells you something about how the spider lives, but does not identify the species by itself.
Use the small, fairly robust hunting-spider shape, bark habitat and enclosed silk retreat as starting clues. Several Clubiona can occur together; the published life-history study could not reliably identify juveniles to species. A pale sac spider should also be compared with Cheiracanthium, the yellow sac spiders, which belong to a different family. Photograph the animal if it is already exposed. Do not strip bark or open a nursery to check its occupant. The name robusta should remain a possibility until the adult features have been checked.
Identification limit: this guide is a comparison aid. A name match in the identifier does not establish a species record.
Compare similar spiders
Sources and further reading
- Austin: life history of Clubiona robusta
- World Spider Catalog: Clubiona
- Healthdirect: spider-bite first aid
Reviewed 21 September 2026. Identification guide; not a confirmed species diagnosis.
Quick identification
- Small, relatively stout wandering spider
- Silk shelter beneath bark
- No orb or tangle web used to catch prey
- Other Clubiona can occupy the same habitat
What to check next
Photograph the whole spider and its surroundings without disturbing it. Use the clues together; a close match is not a confirmed species identification.
When to seek medical help
For a suspected bite, contact the Poisons Information Centre on 13 11 26. Call 000 for breathing difficulty, collapse or other severe symptoms. Do not wait for an online identification.
Where it is usually seen
Under loose eucalyptus bark and in sheltered woodland situations. Australian records include the South Australian study area; an indoor encounter alone is weak evidence.