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the web of life in southern Africa

Cheiracanthium (long-legged sac spiders)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthropoda > Arachnomorpha > Cheliceriformes > Chelicerata > Euchelicerata > Arachnida > Araneae > Araneomorpha > Family: Miturgidae

Cheiracanthium fulcatum. [image N. Larsen ]

Derived from the Greek "cheiro" meaning "hand" and "akanta" meaning "spine" relating to the male palp.

Cheiracanthium spiders range from 3-12.15 mm in body length and make silk sac retreats, hence the common name of sac spider. They are creamy straw coloured but sometimes the carapace and legs might be slightly darker than the abdomen. The abdomen may present with an indistinct dorsolateral folium mark. Cheiracanthium has a black face and chelicerae and the first pair of legs is noticeably longer than the fourth pair and these they use for detecting and capturing their prey Clubiona resemble Cheiracanthium but have the first pair of legs similar in size to the fourth and if the chelicerae is darker than the carapace it will vary from brown to maroon in colour. Clubiona does not enter buildings.

Long-legged sac spiders are fast and aggressive, free ranging and nocturnal and commonly occur on vegetation. They are important in controlling agricultural insect pests. I have, on more than one occasion found a sac spider gazing up at me from a bunch of grapes in the local supermarket.

They construct a silk-like retreat in a curled leaf or in the heads of Protea flowers. With the onset of summer they find houses an ideal habitat, constructing their sac retreats in the folds of curtains, bedding, clothing, doorframes and corners. Being active at night, it is then that most bites occur when the animal is inadvertently pressed against the body, as the large fangs of this spider are capable of penetrating light fabrics.

Absent only from the polar regions there are 8 species in South Africa with Cheiracanthium furculatum (previously Cheiracanthium lawrencei) responsible for about 70-90% of all spider bites in South Africa. The bites, although not life-threatening, are nasty as the venom of these spiders is cytotoxic.

Text by Norman Larsen