Steatoda borealis

(Hentz, 1850)

Boreal Combfoot

Steatoda borealis is a cobweb spider native to North America, belonging to the Theridiidae. The has been documented in the United States and Canada. Research indicates it competitive displacement from the introduced European Steatoda bipunctata in human-modified , though it persists in forested areas with minimal human disturbance.

Steatoda borealis by (c) Bill Keim, some rights reserved (CC BY), uploaded by Bill Keim. Used under a CC-BY license.

Common Spiders U.S. 277-9 Steatoda borealis by James Henry Emerton (1847 – 1931). Used under a Public domain license.

Cupboard spider Steatoda borealis 6762 by Paul Harrison. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Steatoda borealis: /stiːəˈtoʊdə bɔːˈriːælɪs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Closely resembles the introduced European Steatoda bipunctata in size and coloration. The two species share similar microhabitat preferences, diel activity patterns, and general , making field identification challenging without close examination.

Images

Habitat

Inhabits forested where human influence is minimal. Also found in buildings, bridges, piles of lumber and firewood, and crevices on tree trunks or among rocks—though these latter habitats are increasingly dominated by the introduced S. bipunctata.

Distribution

Native to North America. Documented in the United States and Canada, specifically including Alberta and British Columbia. The ' range overlaps with areas where the introduced S. bipunctata has established.

Behavior

Exhibits diel activity patterns and prey selection similar to those of the introduced S. bipunctata. Has been observed to persist in forest despite competitive pressure from S. bipunctata in more disturbed environments.

Human Relevance

Subject of ecological study regarding competitive displacement by introduced . No documented medical or agricultural significance distinct from other Steatoda species.

Similar Taxa

Steatoda bipunctataEuropean introduced that closely resembles S. borealis in size, color, microhabitat, diel activity, prey selection, , and sexual ; documented to competitively displace S. borealis in human-modified

More Details

Competitive Displacement

A study published in the Canadian Journal of Zoology (1986) documented that S. borealis declined as S. bipunctata increased at study sites over time. Displacement is partial rather than complete, with S. borealis persisting in forest where human influence is minimal. Laboratory tests failed to demonstrate the specific mechanism of displacement through reproductive potential or interspecific aggression differences.