Blistering Ammania vs cobweb spiders

Ammannia baccifera compared with Steatoda grossa

Taxonomic Classification

Rank	Blistering Ammania	cobweb spiders
Kingdom	Plantae (Plants)	Animalia (Animals)
Phylum	Magnoliophyta (Flowering Plants)	Arthropoda (Arthropods)
Class	Magnoliopsida (Dicots)	Arachnida (Arachnids)
Order	Myrtales (Myrtales)	Araneae (Araneae)
Family	Lythraceae	Theridiidae
Genus	Ammannia	Steatoda
Species	Ammannia baccifera	Steatoda grossa

Conservation Status

Blistering Ammania

LC — Least Concern

cobweb spiders

LC — Least Concern

Physical Characteristics

Attribute	Blistering Ammania	cobweb spiders
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Blistering Ammania

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, montane grasslands and shrublands, and mangrove forests and coastal wetlands, among 4 distinct biome types spanning the Indomalayan and Oceanian and Palearctic realms. Populations are also found in montane and highland environments at higher elevations.

Range

Widely distributed across Asia (5 countries), Europe (Greece, Italy, North Macedonia), and Oceania and the Pacific (Palau).

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).

Blistering Ammania

The Blistering Ammania (Ammannia baccifera) is a species in the genus Ammannia. It is currently classified as Least Concern on the IUCN Red List. Found across multiple habitat types including tropical and subtropical moist broadleaf forests, montane grasslands and shrublands, and mangrove forests and coastal wetlands, among 4 distinct biome types spanning the Indomalayan and Oceanian

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.