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Species Cheiracanthium mildei

spider - Cheiracanthium mildei Brown spider - Cheiracanthium mildei yellow sac spider - Cheiracanthium mildei another sac spider - Cheiracanthium mildei spider ID in denver - Cheiracanthium mildei cannibal long-legged sac spider - Cheiracanthium mildei - male Long-legged Sac Spider (Cheiracanthium)? - Cheiracanthium mildei - female from Nova Scotia - Cheiracanthium mildei - male
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Chelicerata (Chelicerates)
Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynae)
Family Cheiracanthiidae
Genus Cheiracanthium (Longlegged Sac Spiders)
Species mildei (Cheiracanthium mildei)
Other Common Names
Yellow Sac Spider, Black-footed Spider
Synonyms and other taxonomic changes

Cheiracanthium was previously placed in Miturgidae and was transferred to the new family Eutichuridae by Ramírez, 2014.(1)(2)
This genus was transferred to family Miturgidae from the family Clubionidae by Ramírez, Bonaldo & Brescovit, 1997.
Explanation of Names
Author: C. L. Koch, 1839
7-10 mm
C. mildei is a relatively small, pale greenish, tan or straw-colored spider. Its front pair of legs is longer than the others, and all four pairs end in double claws.

The male can be recognized by having a pedipalp with 2 equally long tibial apophyses. (C. inclusum appears to have one short apophysis and one long apophysis.)

Holarctic distribution as well as southern South America (Argentina).
They make a resting tube in a rolled leaf or under bark or stones. (3)
More often found inside man-made structures (as opposed to C. inclusum which is found more often outdoors). Habitat is not the best way to separate them, though; genitalia needs to be examined under microscope.
Indoor populations of C. mildei are non-seasonal and can be adult at any time.
Any small invertebrate (e.g. insects).
Life Cycle
After mating, females lay 30-48 eggs, cover them in a thin, white silken sac and guard them. The egg sacs may be found in protected areas, or even wrapped in a folded leaf. All stages of sac spiders make a silken cell (the "sac"), in which they rest when not active.
Being Bitten:
Yellow sac spider bites occur most frequently when the very defensive spider is trapped in clothing.

As Rod Crawford points out, "It turned out that the association of this spider with blisters and lesions was wrong, though accepted by everyone until recently. See the attached paper. I'd say this species ought to be taken off the medical concern list." See full article here.

Sac spiders are classified as hunting spiders. These spiders are very active at night and will emerge from their day resting sacs to run along walls and ceilings in pursuit of prey. If startled, they drop down on draglines and scurry away!

Imported from Europe in the 1940s.
Works Cited
1.The morphology and phylogeny of dionychan spiders
Ramírez, Martín J. 2014. Bulletin of the American Museum of Natural History.
2.World Spider Catalog
3.Spiders and Their Kin: A Golden Guide from St. Martin's Press
Herbert W. Levi, Lorna R. Levi, Nicholas Strekalovsky. 2001. St. Martin's Press.