Eratigena duellica

Distinguished from the closely related Eratigena atrica and E. saeva by subtle morphological differences that were used to restore them as separate species in 2018; precise identification requires examination of genitalia or other detailed morphological features. The giant house spider is larger than most domestic spiders and constructs a distinctive flat sheet web with a tubular retreat at one edge. It may be confused with other large Agelenidae, but its association with human structures in its introduced North American range helps narrow identification.

A large spider with elongated legs and a robust body. The abdomen typically displays a pattern of dark and light markings. As a funnel weaver, it possesses prominent spinnerets for silk production. Sexual dimorphism is present, with mature individuals reaching substantial size relative to other domestic spiders.

Strongly associated with human dwellings, including houses, garages, sheds, and other buildings. In its native European range, it also occurs in natural habitats including rock crevices and under bark. In North America, it is primarily found in and around buildings in urban and suburban settings.

Native to Europe; introduced and established in western North America including British Columbia (Canada), Washington and Oregon (United States). Records from other regions may represent misidentifications or additional introductions.

Adults are most commonly encountered in late summer and autumn, when males wander in search of females. Activity continues year-round within heated buildings.

Feeds on insects and other arthropods that become trapped in its web; observed prey includes flies and other small invertebrates common in domestic environments.

Females deposit eggs in silk egg sacs hidden within the funnel retreat. Spiderlings emerge and disperse, with development proceeding through multiple instars. Males mature and wander to find females, while females may remain in established webs for extended periods.

Constructs a characteristic funnel web with a flat sheet portion and a tubular retreat where the spider waits for vibrations from prey. When disturbed, the spider rapidly retreats into the funnel. Males exhibit wandering behavior during the mating season, often entering living spaces and causing alarm due to their size.

An opportunistic predator of household insects and other arthropods; contributes to regulation of indoor pest populations. Serves as prey for various spider predators including other spiders and parasitoid wasps.

Often evokes fear due to its large size and rapid movements, though it is not considered medically significant. The species was popularized by humorist David Sedaris in his essay "April in Paris" from the book "When You Are Engulfed in Flames," in which he described keeping a specimen as a pet and feeding it flies. Frequently found in basements, garages, and dark corners of homes in its introduced range.

• Eratigena atricaAlso called the giant house spider and historically confused with E. duellica; separated as distinct species in 2018 based on morphological differences
• Eratigena saevaThird species in the complex restored to full species status in 2018; morphologically similar and requires detailed examination for reliable separation

• funnel weaver
• house spider
• introduced species
• synanthropic

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bug Eric: December 2011
• Bug Eric: Spider Sunday: Spiders and Celebrities