Coastal Silver-stiletto vs Ko`oko`olau

Acrosathe annulata compared with Bidens campylotheca

Key Differences

Coastal Silver-stiletto is Least Concern while Ko`oko`olau is Vulnerable.

Taxonomic Classification

Rank	Coastal Silver-stiletto	Ko`oko`olau
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Arthropoda (Arthropods)	Magnoliophyta (Flowering Plants)
Class	Insecta (Insects)	Magnoliopsida (Dicots)
Order	Diptera (Diptera)	Asterales (Daisies & Sunflowers)
Family	Therevidae	Asteraceae (Daisy Family)
Genus	Acrosathe	Bidens
Species	Acrosathe annulata	Bidens campylotheca

Conservation Status

Coastal Silver-stiletto

LC — Least Concern

Ko`oko`olau

VU — Vulnerable

Physical Characteristics

Attribute	Coastal Silver-stiletto	Ko`oko`olau
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.

Ko`oko`olau

Habitat

Found across multiple habitat types including temperate broadleaf and mixed forests, temperate coniferous forests, and temperate grasslands and steppes, among 4 distinct biome types within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

Found in Turkey. Currently classified as Vulnerable 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.