Badumna longinqua

Distinguished from the closely related Badumna insignis (black house spider) by lighter grey coloration versus darker brown to black. The messy, ladder-like web with a tubular retreat distinguishes it from orb-weavers and other web-building spiders. The combination of grey body coloration, purplish-brown banded legs, and synanthropic habitat separates it from most native spiders in introduced ranges.

Medium-sized spider with females reaching up to 15 mm body length, males up to 11 mm. Cephalothorax and abdomen covered with light-grey hairs and spot-like markings. Legs purplish-brown with hairs arranged in stripes. Carapace brown, darkening toward chelicerae and eyes. Eight small black eyes, with front middle pair approximately 1.5 times larger than surrounding eyes. Abdomen ovate.

Strongly synanthropic; primarily found in urban and artificial environments. Constructs webs in window frames, wall crevices, under furniture, on car bodies and mirrors, rubbish bins, urban park benches and tree bases, and artificial flowers in cemeteries. In some regions (e.g., United States), also found in woodlands, coastal areas, agricultural ecosystems, and vineyards. In native Australia, occurs in tree trunks, rock walls, leaves, and green shrubs. Avoids natural forest habitats in most introduced ranges. Shows tolerance for varied temperate climates.

Native to eastern Australia. Introduced and established in New Zealand (widespread on North Island, less common in southern and western South Island), Japan, United States, Mexico, Uruguay, Argentina (Buenos Aires Province), Brazil (Rio Grande do Sul), Britain, Germany, Netherlands, South Africa, and Canada. Dispersal facilitated by human transport via ships, planes, trains, and merchandise.

Males actively seek females during warmer months from summer through early autumn. Females may remain in the same web year-round. Nocturnal activity pattern with web maintenance and feeding occurring at night.

Opportunistic web-building predator. Prey consists primarily of flies (often comprising over half of diet), with additional capture of small psyllids, ants, and moths. Capable of subduing larger prey including wasps, bees, bumblebees, and cicadas. Prey is bitten and further entangled upon capture; if caught during daytime, the spider retreats and feeds after nightfall. Digestion occurs through liquefaction via injected or regurgitated digestive fluids.

Lifespan approximately two years based on congeneric Badumna insignis, though not formally documented. Females potentially remain in the same web for their entire lives. Sexually mature males leave their webs to search for females. Courtship behavior not formally described.

Constructs messy, ladder-like cribellate webs with tubular retreat in cracks or crevices. Web maintained and expanded nightly, becoming increasingly untidy over time. Nocturnal: remains hidden in retreat during daytime, emerges at night for web maintenance and feeding. Generally does not wander into households in search of mates. Solitary except during mating period. Dispersal via human-mediated transport and potentially ballooning (unconfirmed for this species).

Generalist predator of insects in urban and agricultural ecosystems. Serves as prey for white-tailed spiders (Lampona spp.), cellar spiders (Pholcus phalangioides), birds, and mammals including New Zealand short-tailed bats. Subject to parasitism by wasps and flies. As an invasive species, may compete with native web-building spiders for habitat and prey resources in introduced ranges.

Common household and urban spider that may cause concern due to web messiness on structures. Not considered medically significant. Accidental introduction via global trade and transport has facilitated its establishment as a cosmopolitan urban species. Presence in agricultural ecosystems (vineyards, plantations) may provide incidental pest control of flying insects.

• Badumna insignisLarger congeneric species with darker brown to black coloration; in New Zealand restricted to northern North Island versus widespread distribution of B. longinqua
• Pholcus phalangioidesCellar spider with similar synanthropic habitat but constructs irregular tangled webs rather than ladder-like webs; has extremely long, thin legs compared to more robust B. longinqua

• synanthropic
• invasive
• nocturnal
• web-building
• cribellate

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• marronoid phylogram - Entomology Today
• The invasive spider Badumna longinqua (L. Koch, 1867) (Araneae: Desidae) in Argentina: new distributional records, with notes on its expansion and establishment
• First records of the invasive spider Badumna longinqua (L. Koch) (Desidae) in southern Brazil with notes on the habitats and the species’ dispersion
• Are you what you eat? A highly transient and prey‐influenced gut microbiome in the grey house spider Badumna longinqua
• Introduction, distribution and habitats of the invasive spiderBadumna longinqua(L. Koch, 1867) (Araneae: Desidae) in Uruguay, with notes on its world dispersion