Brook Alder vs Coastal Silver-stiletto

Alnus maritima compared with Acrosathe annulata

Key Differences

Brook Alder is Endangered while Coastal Silver-stiletto is Least Concern.

Taxonomic Classification

Rank	Brook Alder	Coastal Silver-stiletto
Kingdom	Plantae (Plants)	Animalia (Animals)
Phylum	Magnoliophyta (Flowering Plants)	Arthropoda (Arthropods)
Class	Magnoliopsida (Dicots)	Insecta (Insects)
Order	Fagales (Beeches & Oaks)	Diptera (Diptera)
Family	Betulaceae	Therevidae
Genus	Alnus	Acrosathe
Species	Alnus maritima	Acrosathe annulata

Conservation Status

Brook Alder

EN — Endangered

Coastal Silver-stiletto

LC — Least Concern

Physical Characteristics

Attribute	Brook Alder	Coastal Silver-stiletto
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Brook Alder

Habitat

Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

Range

Distributed across Belgium, France, Netherlands, and United Kingdom. Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

Coastal Silver-stiletto

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Brook Alder

The Brook Alder (Alnus maritima) is a species in the genus Alnus. It is currently classified as Endangered on the IUCN Red List. Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

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.