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Latrodectus spp., Widow spiders

Clinical entries


  1. L. antheratus
  2. L. apicalis
  3. L. bishopi 
  4. L. cinctus 
  5. L. corallinus
  6. L. curacaviensis 
  7. L. dahli 
  8. L. diaguita
  9. L. elegans
  10. L. erythromelas
  11. L. geometricus 
  12. L. hasselti
  13. L. hesperus 
  14. L. hystrix 
  15. L. indistinctus
  16. L. karrooensis
  17. L. katipo
  18. L. lilianae
  19. L. mactans 
  20. L. menavodi 
  21. L. mirabilis
  22. L. obscurior
  23. L. pallidus
  24. L. quartus
  25. L. renivulvatus
  26. L. revivensis 
  27. L. rhodesiensis 
  28. L. tredecimguttatus 
  29. L. variegatus
  30. L. variolus


All species were originally described as subspecies of L. mactans. Even today L. apicalis, L. curacaviensis, L. dahli, L. elegansL. geometricus and L. indistinctus are still sometimes seen as subspecies of L. mactans. The species L. mactans listed above is equivalent to L. mactans mactans in the old sense.


Arachnida; Araneae; Araneomorphae (Labidognatha); Theridiidae

Common names

Widow spiders, Witwenspinnen
3. Red widow, Red-legged widow spider 
4. Knoppie, Button spider 
11. Brown widow spider 
12. Red-back spider 
15. Knoppie, Button spider, Black widow spider 
19. Black widow spider, eigentliche schwarze Witwe
28. Malmignatte, Karakurt 


Latrodectus spp.: throughout the world between the latitudes 50° north and 45° south.


  1. Paraguay, Argentina
  2. Galapagos Islands
  3. Central and Southern Florida  
  4. Africa, Cape Verde Islands, Kuwait 
  5. Argentina
  6. temperate zones of North and South America, Lesser Antilles
  7. Middle East to Central Asia
  8. Argentina
  9. China, Myanmar, Japan
  10. Sri Lanka
  11. throughout the world in tropical and warm regions 
  12. from India and Southeast Asia to Australia and New Zealand 
  13. western North America, Israel 
  14. Yemen, Socotra 
  15. Namibia, South Africa
  16. South Africa
  17. New Zealand
  18. Spain
  19. probably North America only
  20. Madagascar, Seychelles, Comoro Islands
  21. Argentina
  22. Cape Verde Islands, Madagascar
  23. southern Russia, Iran, Syria, Israel, Egypt, Libya, Cape Verde Islands
  24. Argentina
  25. Africa, Saudi Arabia, Yemen
  26. Israel (Neghev)
  27. southern Africa  
  28. the Mediterranean to China
  29. Chile, Argentina
  30. eastern North America.


Latrodectus species possess a typically round abdomen. The cephalothorax (head and anterior part of the body) appears small in comparison. Eyes arranged in 2 rows (Fig. 4.40b). Body length in females 1–1.8 cm, in males barely more than 0.5 cm. Only female animals cause envenoming in humans.





Fig. 4.40 Latrodectus mactans.
a Appearance. Note the (truncated) hourglass-shaped marking on the ventral surface of the abdomen.
b Carapace with the arrangement of the 8 eyes.


Colouring from shiny black to brownish. L. mactans and L. geometricus possess a red marking in the form of an hourglass or two triangles on the ventral surface of their abdomen, although the shape of this marking may show considerable differences between individuals.

L. geometricus also has markings in the form of geometrical patterns on the dorsal surface of the abdomen. In L. hasselti and L. indistinctus there is usually a red or orange longitudinal stripe along the dorsal surface of the abdomen. In L. tredecimguttatus there may be several red spots distributed over the dorsal surface of its abdomen or there may be none at all. Juvenile animals often have markings that differ from those in adults.

"Black widows" are found in the most varying habitats but usually avoid forested areas. They live in both farmed and unfarmed regions and in some regions are even found in cities. L. tredecimguttatus appears to prefer grain fields in southern Europe. L. mactans, L. hesperus and L. hasselti are frequently found in and around human habitations, e.g. in tool sheds, garages, cellars or outdoor toilets, but also in wood or junk left lying around. Several species at least are typical synanthropes and their wide distribution was thus greatly facilitated by humans.

They often construct their webs close to the ground. The webs are very irregular in construction. New threads are constantly added to the old web, which makes the webs very stable. The centre of the web is usually located under a stone or branch or in a crack in a wall and forms a basket-like recess which the spider retreats into.

Widow spiders are not at all aggressive and practically only ever bite when squashed. This can happen if they get stuck between a piece of clothing and the victim's skin or when carelessly picking up tools, bundles of grain etc.


A Latrodectus bite is not always noticed. Latrodectism, the term for the typical symptoms of envenoming caused by these spiders, can occur in warm to tropical regions on all continents. Epidemic-like occurrences of envenoming are associated with periodic mass reproduction of these spiders, the causes of which are probably associated with climatic factors.

Accidents with species living in the wild such as L. tredecimguttatus, L. indistinctus or L. mactans most commonly occur during farming work in grain or cotton fields or in vineyards. However, accidents may also occur in other situations in which humans enter the natural distribution areas of these spiders, e.g. while camping or during military manoeuvres. L. mactans bites in outdoor toilets are not uncommon.

In countries where there are mainly species that live in the wild, the incidence of bites is highest during the summer months. In the regions where there are species that live in human habitations, accidents may occur throughout the year. In a study of 45 Latrodectus bites in South Africa that were treated over a period of 4 years, 30 were caused by L. indistinctus and 15 by L. geometricus. It was apparent from this study that envenoming caused by L. indistinctus was markedly more severe than that caused by L. geometricus, which only led to mild symptoms and signs of envenoming (Müller 1993).

There are occasional reports of the danger of spiders from the genus Steatoda (also part of the Theridiidae family) (Maretic 1978b). One case of envenoming due to Steatoda nobilis was documented in England (Warrell et al. 1991). This species, originally native to the Canary Islands, appears to be establishing itself in the south of England.

Literature (biological)

Abalos and Baez 1967, Bellmann 2001, Bettini 1964, Kaston 1970, Levi 1959, 1966, Maretic 1978a, 1979, Martindale and Newlands 1982, Raven and Gallon 1987b, Shulov 1966, Sutherland 1983

The World Spider Catalog