Badumna

Distinguished from similar desid spiders by the combination of cribellate silk production, carapace coloration (pale to dark brown with mixed hair types), and the patterned opisthosoma with dark striping or spotting. The synanthropic species B. longinqua and B. insignis are frequently encountered in human structures and can be identified by their web architecture and habitat association. Separation from other cribellate families (e.g., Amaurobiidae, Dictynidae) requires examination of eye arrangement, spinneret structure, and genitalic morphology.

Medium to large cribellate spiders. The carapace ranges from pale brown to darker brown, bearing long or small brown hairs alongside smaller white hairs. The opisthosoma displays dark striping or spotting. As cribellate spiders, they possess a cribellum—a silk-producing plate used to generate hackled silk for prey capture.

Native species occupy intertidal and terrestrial habitats in the Indo-Australian region. Introduced populations, particularly B. longinqua and B. insignis, are strongly synanthropic, occurring in urban environments including public parks, window frames, building exteriors, and cemeteries. In Brazil, B. longinqua has been documented in window frames and artificial structures rather than natural vegetation.

Native to the Indo-Australian region, with most species endemic to Australasia. Introduced populations established in: California (USA) along the Pacific coast; Japan; Germany; New Zealand; Uruguay; Argentina (Buenos Aires Province); and southern Brazil (Rio Grande do Sul).

Active predators that capture prey in webs. B. longinqua has been documented consuming crickets and fruit flies in feeding experiments. Gut microbiome analysis indicates diet directly influences microbial community assembly, with prey-derived microbes transiently colonizing the spider's gut.

Nocturnally active sit-and-wait predators. B. insignis exhibits risk-sensitive foraging behavior: during daylight hours, spiders remain within retreats and take longer to reach prey, reducing foraging success but minimizing predation risk. At night, spiders position themselves exposed at retreat edges, enabling rapid prey capture and faster escape from predators. Web-building occurs on artificial structures in urban environments.

Generalist predators in both native and introduced ranges. In invaded regions, B. longinqua functions as an established invasive species in urban ecosystems. The transient, prey-influenced gut microbiome suggests limited vertical transmission of symbionts, with microbial communities shaped primarily by consumed prey rather than host-specific coevolution.

Frequently encountered around human structures due to synanthropic habits. Considered harmless to humans. B. insignis is commonly known as the 'black house spider' or 'black window spider' due to its association with buildings. Introduced populations have become established in urban areas across multiple continents, sometimes mistaken for medically significant spiders due to dark coloration.

• AmaurobiusAlso cribellate spiders that occur in human structures, but differs in geographic distribution (primarily Holarctic) and specific web architecture
• StiphidionMarronoid spider in family Stiphidiidae with similar cribellate silk production; distinguished by web structure and habitat preferences
• DesisIntertidal desid spider that shares family-level traits, but occupies marine shoreline habitats rather than terrestrial or synanthropic environments

The common name 'black window spider' for B. insignis may cause confusion with the medically significant widow spiders (Latrodectus, Theridiidae), which are unrelated and possess potent neurotoxic venom. Badumna species are harmless to humans.

• cribellate
• synanthropic
• invasive
• nocturnal
• sit-and-wait predator
• marronoid
• intertidal

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• marronoid phylogram - Entomology Today
• Foraging behaviour and the risk of predation in the black house spider, Badumna insignis (Desidae)
• 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