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Steatoda triangulosa

Steatoda triangulosa


Family: Theridiidae
Order: Araneae
Class: Arachnida
Phylum / Division: Arthropoda
Kingdom: Animalia

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Description


Belongs to the cobweb spider family and is distinguished by its moderate body size, with adult females measuring between 3 and 6 millimeters in length, while males are slightly smaller, ranging from 3 to 5 millimeters. It features a yellowish-brown to brownish-orange cephalothorax that is covered in fine, short hairs. Its abdomen is noticeably globose and rounded, displaying a highly characteristic dorsal pattern consisting of purplish-brown triangles or reddish-brown triangles contrasting against a pale yellow or cream-colored background, which gives the species its distinctive appearance. The slender legs are pale yellow and showcase dark, distinct bands or rings at the joints. It possesses eight eyes arranged in two rows, with the lateral eyes being distinctly separated from one another.

Geographical distribution: Holds an extensive, cosmopolitan distribution that has been significantly aided by human transportation and global trade. It is believed to be native to Eurasia and the Mediterranean basin, but it is currently established across major portions of North America (extending from southern Canada throughout the United States), South America (including countries such as Argentina, Brazil, and Uruguay), as well as various temperate zones of Asia, Africa, and Oceania, showing a remarkable ability to colonize new geographic territories.

Habitat: Displays a highly pronounced synanthropic preference, meaning it is most frequently encountered in and around human-made structures. It commonly occupies dark, dry, and undisturbed interior microhabitats such as basements, attics, closets, crawl spaces, under large furniture, window frames, garages, and sheds. In natural settings, although far less common, it can be found under rocks, inside caves, and within tree bark crevices, consistently seeking shelter from direct sunlight and avoiding overly humid conditions.

Feeding: Functions as an opportunistic and highly efficient generalist predator. Its diet is remarkably diverse, consisting of various crawling and flying arthropods such as ants, flies, mosquitoes, pillbugs, beetles, and other spiders. It is notable for its ecological capacity to capture and overpower prey significantly larger and more dangerous than itself, including brown recluse spiders (Loxosceles reclusa), hobo spiders, and various ticks, making it a highly beneficial natural pest control agent within domestic environments.

Behavior: Exhibits a primarily nocturnal lifestyle, spending daylight hours concealed in crevices near the margins of its web. It constructs an irregular, tangled, three-dimensional web made of sticky silk, typically referred to as a cobweb, which lacks any geometric symmetry. It is not an aggressive species towards humans and will typically retreat or exhibit tanatosis (feigning death) when disturbed; bites are exceptionally rare, and its venom, while potent enough to rapidly immobilize prey, is of no medical significance to humans, causing only mild localized discomfort and temporary redness.

Reproduction: Takes place throughout the year in temperature-controlled indoor environments, though it is concentrated in spring and summer outdoors in temperate zones. After a cautious courtship ritual where the male vibrates the web to signal his presence and avoid sexual cannibalism, copulation occurs. Females produce several spherical, papery egg sacs over their lifespan, which are translucent white or cream-colored and measure about 2 to 3 millimeters in diameter. Each sac contains between 30 and 40 eggs. The spiderlings hatch within a few weeks and quickly disperse, often using a ballooning technique with silk threads.

Conservation status: Has not been formally evaluated by the International Union for Conservation of Nature (IUCN) for inclusion on the Red List. Because it is highly adaptable, widely distributed, and extremely abundant within human-altered landscapes globally, its population trends are considered exceptionally stable, and the species faces no imminent conservation threats or risks of extinction.



Compilation and publication: EcoRegistros – 03/09/2026




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Foto
Photography ID: 151896
  Adult

Castelar
Buenos Aires
Argentina
06/01/2016
Román Montero
Foto
Photography ID: 148684
  Adult

Castelar
Buenos Aires
Argentina
05/03/2016
Román Montero
Foto
Photography ID: 125230
  Adult

Castelar
Buenos Aires
Argentina
11/14/2015
Román Montero
Foto
Photography ID: 105581
  Adult

Castelar
Buenos Aires
Argentina
07/11/2015
Román Montero
Foto
Photography ID: 104145
  Adult

Castelar
Buenos Aires
Argentina
06/29/2015
Román Montero
Foto
Photography ID: 101424
  Adult

Castelar
Buenos Aires
Argentina
06/05/2015
Román Montero



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Page 1
Record IDDateExact timeCountryProvince / departmentPlaceFilmedPhotographedRecorded vocalObservedHeardWounded or deadNumber of individualsUser or BibliographyDetail
152553102/01/2022ArgentinaBuenos AiresPlaza Cumelén (plaza del Vagón), CastelarRomán Montero
133711926/12/2020ArgentinaBuenos AiresCastelarRomán Montero
43956301/06/2016ArgentinaBuenos AiresCastelarRomán Montero
43082603/05/2016ArgentinaBuenos AiresCastelarRomán Montero
38396901/01/2016ArgentinaBuenos AiresCastelar1Román Montero
36224714/11/2015ArgentinaBuenos AiresCastelarRomán Montero
30317611/07/2015ArgentinaBuenos AiresCastelarRomán Montero
29958429/06/2015ArgentinaBuenos AiresCastelarRomán Montero
29154805/06/2015ArgentinaBuenos AiresCastelarRomán Montero
Page 1

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Recommended citation
Please use the following reference when citing this species account.
EcoRegistros. 2026. Steatoda triangulosa – Species account. Accessed from www.ecoregistros.org on 24/09/2026.