Coastal Silver-stiletto vs spreading threadwort

Acrosathe annulata compared with Cephaloziella divaricata

Key Differences

• Coastal Silver-stiletto is Least Concern while spreading threadwort is Endangered.

Taxonomic Classification

Rank	Coastal Silver-stiletto	spreading threadwort
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Arthropoda (Arthropods)	Marchantiophyta (liverwort)
Class	Insecta (Insects)	Jungermanniopsida (Jungermanniopsida)
Order	Diptera (Diptera)	Jungermanniales (Jungermanniales)
Family	Therevidae	Cephaloziellaceae
Genus	Acrosathe	Cephaloziella
Species	Acrosathe annulata	Cephaloziella divaricata

Conservation Status

Coastal Silver-stiletto

LC — Least Concern

spreading threadwort

EN — Endangered

Physical Characteristics

Attribute	Coastal Silver-stiletto	spreading threadwort
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.

spreading threadwort

Habitat

Native to Europe and North America and South America, inhabiting ecosystems characteristic of the region.

Range

Widely distributed across Europe (5 countries), North America (United States), and South America (Brazil). Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

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