cobweb spiders vs Common corncockle

Steatoda grossa compared with Agrostemma githago

Key Differences

cobweb spiders is Least Concern while Common corncockle is Critically Endangered.

Taxonomic Classification

Rank	cobweb spiders	Common corncockle
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Arthropoda (Arthropods)	Magnoliophyta (Flowering Plants)
Class	Arachnida (Arachnids)	Magnoliopsida (Dicots)
Order	Araneae (Araneae)	Caryophyllales (Caryophyllales)
Family	Theridiidae	Caryophyllaceae
Genus	Steatoda	Agrostemma
Species	Steatoda grossa	Agrostemma githago

Conservation Status

cobweb spiders

LC — Least Concern

Common corncockle

CR — Critically Endangered

Physical Characteristics

Attribute	cobweb spiders	Common corncockle
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).

Common corncockle

Habitat

Found across multiple habitat types including montane grasslands and shrublands, tropical and subtropical moist broadleaf forests, and temperate coniferous forests, among 13 distinct biome types. Populations are also found in montane and highland environments at higher elevations.

Range

Widely distributed across Africa (Lesotho), Asia (7 countries), Europe (24 countries), North America (Canada, Mexico, United States), Oceania and the Pacific (Australia), and South America (Brazil, Chile). Currently classified as Critically Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

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.

Common corncockle

<em>Agrostemma githago</em>, commonly known as common corncockle, is an annual flowering plant in the family Caryophyllaceae. Once a widespread weed of cereal crops across Europe, Asia, and beyond, this species is now Critically Endangered on the IUCN Red List due to the dramatic decline caused by modern agricultural practices, particularly improved grain cleaning and herbicide use. Corncockle is a tall, slender plant covered in silky white hairs, bearing large, solitary pink to purple flowers with distinctive dark veining. Its seeds contain toxic saponin compounds called githagins, which historically contaminated grain supplies. The species now survives primarily in wildflower conservation areas, seed banks, and traditional farmland conservation schemes. It typically grows in open, disturbed arable soils with full sun exposure. Biological traits of this species remain poorly documented in the scientific literature.