Common House Spider Identification: P. tepidariorum

About the Common house spider

The common house spider, Parasteatoda tepidariorum, is a small cobweb-building theridiid associated with buildings around much of the world. In Australia it is still indexed by the Australian Faunal Directory and Atlas of Living Australia under the older combination Achaearanea tepidariorum, so both names can appear in museum records and search results. Look for a pea-sized spider with a high rounded abdomen, fine ringed legs and mottled cream, tan, brown or charcoal markings, hanging upside down in a loose three-dimensional tangle web. Do not identify it from “brown spider in a corner” alone: native white porch spiders, red house spiders, cupboard spiders, redbacks and lace-web house spiders can occupy the same structures. Web form, body proportions, egg-sac shape and clear dorsal photographs can support a likely match, but exact small-theridiid identification may require a mature specimen and microscopic genital characters.

Exact-species specimen views

These licensed exact-taxon photographs show useful anatomy and variation. Use each caption for record and image context; no single image set represents every colour, posture or habitat.

How to identify Parasteatoda tepidariorum

Start with the theridiid body plan and web. An adult female common house spider has a small dark cephalothorax, a much larger high rounded abdomen and long fine legs. University extension guidance places females at roughly 5–8 mm body length and males at about 3.8–4.7 mm; measure the body only, not the leg span. The abdomen often has a pale ground colour dusted with white speckles and darker paired chevrons, V-shapes or irregular patches toward the rear. Legs are translucent yellow-brown to darker brown with contrasting rings. Like other comb-footed spiders, the last leg pair carries serrated bristles used to throw sticky silk over prey, but this is a microscope character, not something to inspect on a live spider. A likely field match combines these proportions, banded legs, mottled abdomen and an irregular cobweb. Species confirmation may require adult genital anatomy because several Australian theridiids overlap in colour, size and household habitat.

Clues that are not enough on their own

• A messy web in a house by itself, because many comb-footed spiders use household corners
• Brown or grey colour alone; P. tepidariorum varies widely and several unrelated house spiders are brown
• No visible red stripe in one photograph, because redback markings can be reduced, hidden or absent in some individuals
• The everyday label “house spider”, which is also used for Badumna, Steatoda, Nesticodes and other spiders
• A bathroom, garage or window location without body proportions, leg banding, web form and a clear dorsal view

Colour, sex and life-stage variation

Colour varies far more than the name suggests. Females may be pale cream-grey, golden tan, chocolate brown or almost charcoal, and the mottled abdominal pattern can be crisp, faint or partly obscured by the spider’s posture. A well-fed or egg-bearing female has an especially swollen abdomen; males are smaller, slimmer-bodied and leggier with enlarged palps, while juveniles can be pale and weakly patterned. Camera flash can wash a pale spider almost white or turn brown joints red. The three licensed photographs retained here are exact P. tepidariorum from New Zealand, not Australian locality records: Don Horne’s pale female hero shows body proportions while the two supporting females show darker, more strongly patterned variation and prey-wrapping posture. Use them for anatomy and variation, not as evidence that every Australian household spider is this species.

Behaviour, web and retreat

The web is a loose, irregular three-dimensional network anchored to firm edges rather than a neat orb or a flat woolly lace sheet. The spider usually rests upside down within or beside the tangle and responds to vibrations by running along silk, throwing more sticky thread and wrapping small flies, mosquitoes, moths, beetles or other household invertebrates. Productive webs can accumulate prey remains and dust, while an unproductive site may be abandoned and leave the familiar empty “cobweb”. Females suspend distinctive brown, papery, often pear-shaped egg sacs within the web; several sacs of different ages may be present. More than one female can build nearby where shelter and prey are plentiful, but proximity is not proof of cooperative social behaviour. Web architecture and egg sacs are stronger identification clues than room type, yet closely related theridiids can still produce similar tangles.

Australian distribution

P. tepidariorum is a human-associated cosmopolitan species transported widely with buildings and goods. Australian records need a nomenclature note: the Australian Faunal Directory and Atlas of Living Australia currently present the taxon as Achaearanea tepidariorum, the older combination, while modern international and extension sources use Parasteatoda tepidariorum. The Atlas currently maps 48 records to that taxon concept; supplied Australian state data include Queensland, Victoria, New South Wales, South Australia and Western Australia, which are the filters used here. Those records are uneven and include historical identifications, so they do not prove that the species is common throughout each state or absent elsewhere. Tasmania, the ACT and Northern Territory were removed from this profile because the current exact-taxon Atlas evidence did not support them. Preserve the locality and date with a photograph, but expect close Australian theridiids to require expert review.

What to do if you find one

If the spider is in an out-of-the-way web and nobody is at risk, leaving it alone allows it to continue catching small indoor insects. For relocation, place a wide container around the spider and use a stiff card only when hands can stay well clear; alternatively remove the whole web with a long-handled brush into a container outdoors. Wear gloves for dusty stored items, but never pinch or squash a hidden spider through clothing or fabric. To reduce repeated webs, vacuum old silk and egg sacs, seal gaps around windows and storage, reduce insect-attracting lights and keep seldom-moved objects tidy. Do not spray or destroy every brown corner spider solely because it resembles a redback. If the abdomen is glossy dark, a red or orange mark is present, or the spider cannot be clearly separated from a redback or cupboard spider, use the comparison pages and avoid handling. A skin lesion without a witnessed spider and bite should not be diagnosed from appearance alone.

Compare with similar spiders

Use body shape, web or retreat, location and behaviour together before settling on a likely match.

• White porch spider — White porch spider - Cryptachaea gigantipes was historically confused with P. tepidariorum in Australasia. It is usually paler, lives conspicuously under eaves and porches, and has extremely long front legs; in males each long first-leg segment can exceed the body length.
• Red house spider — Red house spider - Nesticodes rufipes is another small household theridiid, but is usually more uniformly reddish brown through the legs and front body with a darker rounded abdomen. Pattern, web and genital anatomy may still be needed for a confident species call.
• Brown house spider / cupboard spider — Brown house spider / cupboard spider - Steatoda species are generally darker, smoother and more glossy, often with a broader oval abdomen and less delicate mottling. They use sheltered tangle webs and can cause clinically important pain, so do not handle a dark specimen to inspect it.
• Redback spider — Redback spider - Latrodectus hasselti females are usually glossy black or dark brown with a red or orange dorsal stripe and ventral hourglass, but markings can be incomplete or obscured. Juveniles and males are patterned differently; never use one missing red mark as the only exclusion.

Sources for this profile

These accessible authoritative sources support the identification and bite-safety context on this page.

• Australian Faunal Directory: Achaearanea tepidariorum
• Atlas of Living Australia: Achaearanea tepidariorum
• Australian Museum: White Porch Spider comparison
• Australian Museum: Web2Spider tangle-web guide
• Zootaxa: Australasian synanthropic theridiid revision
• Penn State Extension: Common House Spider
• healthdirect: Spider bites

Profile review

Published by Spider Identifier Australia. Last factual review: 10 August 2026.