Coastal Silver-stiletto vs False widow

Acrosathe annulata compared with Steatoda bipunctata

Taxonomic Classification

Rank	Coastal Silver-stiletto	False widow
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Arthropoda (Arthropods)	Arthropoda (Arthropods)
Class	Insecta (Insects)	Arachnida (Arachnids)
Order	Diptera (Diptera)	Araneae (Araneae)
Family	Therevidae	Theridiidae
Genus	Acrosathe	Steatoda
Species	Acrosathe annulata	Steatoda bipunctata

Evolutionary Relationship

Coastal Silver-stiletto and False widow share a common ancestor at the Phylum level: Arthropoda. (Arthropods)

Conservation Status

Coastal Silver-stiletto

LC — Least Concern

False widow

LC — Least Concern

Physical Characteristics

Attribute	Coastal Silver-stiletto	False widow
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Coastal Silver-stiletto

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

False widow

Habitat

Typically found in terrestrial habitats from forests to deserts.

Range

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

Coastal Silver-stiletto

Coastal silver stiletto (Acrosathe annulata) is a slender robber fly in the family Therevidae, native to northwestern Europe, including the United Kingdom, France, the Netherlands, Belgium, and Scandinavia. Adults are found on coastal sand dunes and sandy heathland, where they perch on bare sand to ambush small flying insects. Stiletto flies in the family Therevidae are characterised by a slender body, long pointed abdomen, and predatory habits; adults prey on a variety of small dipterans and other flying insects during warm, sunny periods. Larvae develop in sandy soil, where they are also predatory, feeding on other invertebrate larvae. Acrosathe annulata is a habitat specialist restricted to open, sandy coastal habitats with sparse vegetation—environments that have declined substantially across northwestern Europe due to dune stabilisation, recreational disturbance, and the cessation of traditional dune management. The IUCN lists it as Least Concern, though regional conservation bodies in the United Kingdom have flagged population declines. It is considered an indicator of high-quality coastal sand dune habitats and is monitored through national invertebrate surveys.

Shared Countries

Both species can be found in 4 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden