The term “cupboard spider” is a collective, common name used to describe several small, house-dwelling spiders found in cluttered, dark areas. These spiders are frequently mistaken for more dangerous relatives, leading to understandable public concern about their potential threat. This article clarifies the actual safety risk posed by these common household inhabitants, addressing whether they are venomous, what a bite entails, and how to safely prevent infestations.
Defining the “Cupboard Spider”
Spiders most frequently identified as “cupboard spiders” belong to the genus Steatoda, commonly known as the False Widow group. Two species often fit this description: Steatoda grossa and Steatoda nobilis. These are small spiders, with females typically ranging from 6 to 10.5 millimeters in body length.
They are characterized by a smooth, shiny, and noticeably bulbous abdomen that is often dark brown, purplish-brown, or black. While they resemble the true Black Widow (Latrodectus species), they lack the distinct, bright red hourglass marking. Cupboard spiders build irregular, tangled webs (cobwebs) in undisturbed, low-light locations. Their preferred habitats include the backs of cabinets, storage closets, basements, garages, and sheds, which is how they earned their common name.
Venom vs. Poison: Clarifying the Threat
A crucial distinction exists between poisonous and venomous organisms. A creature is poisonous if it causes harm when its toxins are inhaled, ingested, or absorbed through the skin. Conversely, an animal is venomous if it injects a toxin into another creature, typically through a bite or sting.
Cupboard spiders, like nearly all spider species, are venomous, possessing venom glands and fangs (chelicerae) to inject toxins for subduing prey. The venom of Steatoda species contains neurotoxic and cytotoxic components, sharing some similarities with the venom of the true Black Widow spider. However, the cupboard spider’s venom is significantly less potent and is generally considered to be of mild medical importance to humans. Bites usually occur only defensively, such as when a spider is accidentally trapped against the skin.
Typical Bite Symptoms and Necessary Action
Bites from a cupboard spider are rare, and the reaction for most people is localized and mild, often compared to the discomfort of a bee or wasp sting. The immediate symptom is typically a sharp, momentary pain at the site of the bite, followed by localized redness, mild swelling, and itching. These minor symptoms usually subside within a few hours to a day, although some individuals may experience a prolonged, dull ache.
To treat a mild bite, first wash the area thoroughly with soap and water to prevent secondary bacterial infection. Applying a cold compress or ice pack can help reduce swelling and discomfort. Medical attention becomes necessary if the localized reaction worsens significantly, if signs of infection appear, or if systemic symptoms develop. Signs of a secondary infection include spreading redness, increased warmth, pus formation, or pain that persists or worsens after 24 hours. Rarely, systemic symptoms like fever, muscle cramps, nausea, or headache may occur, which warrants consultation with a healthcare professional.
Preventing Infestations and Safe Removal
Controlling the presence of cupboard spiders involves reducing the availability of their preferred dark, sheltered habitats and their food sources. A primary prevention strategy is to regularly reduce clutter, especially in storage areas like garages, attics, and basements, which eliminates their hiding spots. Sealing small gaps, cracks, and entry points around windows, doors, and utility penetrations prevents spiders from entering the home.
Removing webs and egg sacs regularly with a vacuum cleaner is an effective method of control, as this physically eliminates the spiders and prevents future generations. For individual spiders found indoors, the safest removal method is to use a cup-and-paper technique: place a cup over the spider, slide a stiff piece of paper underneath to trap it, and then release it outdoors.