cobweb spiders vs False widow

Steatoda grossa compared with Steatoda bipunctata

Taxonomic Classification

Rank	cobweb spiders	False widow
Kingdom same	Animalia (hayvan)	Animalia (hayvan)
Phylum same	Arthropoda (Eklem bacaklılar)	Arthropoda (Eklem bacaklılar)
Class same	Arachnida (Örümceğimsiler)	Arachnida (Örümceğimsiler)
Order same	Araneae (Örümcek)	Araneae (Örümcek)
Family same	Theridiidae	Theridiidae
Genus same	Steatoda	Steatoda
Species	Steatoda grossa	Steatoda bipunctata

Evolutionary Relationship

cobweb spiders and False widow share a common ancestor at the Genus level: Steatoda.

Conservation Status

cobweb spiders

LC — Least Concern

False widow

LC — Least Concern

Physical Characteristics

Attribute	cobweb spiders	False widow
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

cobweb spiders

Habitat

Typically found in terrestrial habitats from forests to deserts.

Range

Widely distributed across Africa (South Africa), Europe (29 countries), North America (Canada, United States), and South America (Ecuador).

False widow

Habitat

Typically found in terrestrial habitats from forests to deserts.

Range

Found across Europe (4 countries) and North America (Canada, United States).

cobweb spiders

The false black widow (Steatoda grossa) is a cosmopolitan cobweb spider in the family Theridiidae, often mistaken for the true black widow due to its similarly dark, globose abdomen, though it lacks the red hourglass marking. Females reach 6–10 millimeters in body length and display a deep purplish-brown to nearly black coloration with faint pale markings on the dorsal abdomen. Originally native to western Europe, Steatoda grossa has spread globally through human commerce, establishing populations in Australia, New Zealand, North America, and other regions where it thrives in human structures including homes, sheds, and outbuildings. The spider constructs a persistent, tangled cobweb in sheltered corners and recesses, where it captures woodlice, ants, beetles, and other arthropods—notably targeting invertebrates that many other spiders avoid. The venom of S. grossa causes steatodism, a syndrome of localized pain, sweating, and systemic discomfort that is rarely serious but can cause significant distress. Interestingly, the antivenin produced for Latrodectus (true widow) spider bites has been shown to effectively treat Steatoda envenomations, underscoring the phylogenetic relatedness of these genera. Females produce several egg sacs during a season, each containing dozens of eggs wrapped in distinctive silken cocoons. The species is classified as Least Concern given its expanding global distribution facilitated by human activity.

Shared Countries

Both species can be found in 5 countries:

🇧🇪 Belgium 🇨🇦 Canada 🇩🇰 Denmark 🇸🇪 Sweden 🇺🇸 United States