Exapion fuscirostre

The combination of small size (2–3 mm), dark gray coloration with a distinct dark band across the elytra, laterally compressed body, and elongated straight snout distinguishes this species from other small weevils. The light brown legs contrast with the darker body.

Dark gray body with a dark band across the elytra. Laterally compressed body shape with a long, straight snout. Legs are light brown. Length 2–3 mm.

Areas supporting Scotch broom (Cytisus scoparius) patches, particularly in Mediterranean climates in its native range and introduced regions. Oviposition is greater in patches with low to medium plant densities.

Native to Europe (Palearctic distribution). Introduced to western United States, now widespread in the Pacific Northwest. Also introduced to New Zealand. Records from Belgium and Norway in native range.

Adults feed on new growth at stem tips. Larvae feed on seeds inside Scotch broom pods.

• Cytisus scoparius - obligateScotch broom; sole known host for oviposition and larval development

Adult females lay eggs inside seed pods of the host plant. Larvae hatch and consume seeds over several weeks, developing within the pod. Specific pupation details and number of generations per year are not documented in available sources.

Adult feeding occurs on new growth at stem tips. Oviposition site selection is influenced by pod width and host plant patch density, with preference for wider pods and low-medium density patches. Oviposition is negatively related to seed abortion rate and presence of other seed-eating insects.

Seed predator of Cytisus scoparius. Acts as a biological control agent reducing reproductive output of this invasive plant. Serves as host for parasitic wasp Pteromalus sequester.

Intentionally introduced as a biological control agent against invasive Scotch broom in the United States and New Zealand. Established populations show promise for reducing Scotch broom spread, though parasitism by Pteromalus sequester may hinder establishment success.

• Other Exapion speciesShare similar body plan and association with legume hosts; require examination of genitalia or host specificity for definitive identification
• Other small brentid weevilsSimilar size and elongated snout; distinguished by specific color pattern and host association

• biocontrol
• invasive species management
• seed predator
• Fabaceae associate

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Effect of Scotch broom, Cytisus scoparius, pod size and patch density on Exapion fuscirostre (Coleoptera, Apionidae) seed weevil oviposition