Fauna
Arachnid

Northern Yellow Sac Spider

Cheiracanthium mildei

Also known as Long-Legged Sac Spider, Milde's Sac Spider, Yellow Sac Spider

Northern yellow sac spiders are agile, nocturnal prowlers that hunt small arthropods without building prey-capture webs. By day, they rest inside dense, tube-like silk sacs constructed in ceiling corners, leaf folds, or behind picture frames. Native to southern Europe, they have successfully colonized urban and suburban environments throughout temperate North America.

NocturnalSynanthropicProwling Hunter
Northern Yellow Sac Spider reference1 / 7
(c) Christian Back, some rights reserved (CC BY), uploaded by Christian Back · cc-by
—observations
—countries
—peak records
Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyFlies, Moths, Leafhoppers
Predators
  • Cellar Spiders
  • Centipedes
  • Insectivorous Birds
ThreatsIndoor pest control and broad-spectrum pesticide spraying
HabitatsHomes, gardens, deciduous foliage, and shrublands
Life span1–2 years
Classification
  1. OrderAraneae
  2. FamilyCheiracanthiidae
  3. GenusCheiracanthium
  4. SpeciesCheiracanthium mildei
Range & activity
Range data is not available yet.
Safe observation
Interaction riskVery high
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is very high
Venomous bite can cause burning pain and local swelling; do not handle with bare hands.
Why it is dangerous
Bites inject venom that can cause sharp pain, erythema, and mild localized swelling similar to a wasp sting.
How to recognize a risky encounter
Recognized by a pale yellowish-green translucent body, dark brown chelicerae, and noticeably elongated front legs.
What to do
Avoid pressing against fabrics or surfaces where the spider may rest, and always relocate it using a container.
Responsible observation
  • Safe Relocation: Place a glass over the spider and slide paper underneath to transport it outside.
  • Check Corners: Inspect upper wall junctions and window frames to spot its daytime silk retreat sac.
Related species
Help improve the field guideSomething wrong?

Report a name, category, or profile issue for review.

Checking your Fauna account…