Scenopinus

Small dark flies with clear wings and bicolored legs (dark femora, paler tibiae). Distinguished from similar Diptera by combination of: compact body, window-fly habit of resting on building surfaces, and association with bird nests or old structures. Some species have completely black halteres, useful for separating from congeners. Adults of S. jerei occur mid- to end June. Identification to species level requires examination of leg coloration and haltere pigmentation.

Small flies, 4–6 mm in length. Body dark brown to black. Wings clear, unpatterned. Legs often bicolored: dark coxae and femora contrasting with paler yellow to orange tibiae. Halteres completely black in some species. Overall compact, somewhat inactive posture.

Boreal forest environments, particularly in association with nests of cavity-nesting birds. Frequently found in and around human structures: old buildings, outhouses, unheated buildings, and on window surfaces. Larvae develop in bird nest boxes and natural cavities.

Palaearctic distribution. Recorded from Finland, Sweden, Denmark, Norway, Russian Karelia, and Central and Southern England. Core range appears to be the boreal forest zone, with some species extending into more temperate European regions.

Adults active mid- to end June in boreal regions. Year-round presence possible in association with heated or sheltered buildings.

Larvae are predatory, feeding on larvae of clothes moths (Tineidae), fleas, and other small invertebrates.

• Strix aluco (tawny owl) - larval development in nest boxesS. jerei reared from nest box material
• cavity-breeding birds (tits, owls) - larval development in nestsgeneral association across genus

Larvae develop in nests of cavity-nesting birds, including both natural cavities and artificial nest boxes. Larvae have been reared from nest box material collected in 2013 and 2018. Adults emerge in mid-summer. Pupation and detailed developmental stages not described.

Adults tend to be inactive, often found resting on windows of old buildings. Adults collected indoors have been taken directly to vials, suggesting limited flight activity when disturbed. Larvae remain within bird nest substrates.

Predatory component of bird nest invertebrate communities in boreal forest ecosystems. Larvae contribute to regulation of populations of clothes moths and fleas within nest microhabitats.

Occasional presence in buildings, particularly older structures. Larval predation on clothes moth larvae may provide minor benefit in protecting stored materials and bird nest boxes.

• Scenopinus vitripennisS. jerei was previously misidentified as this species; distinguished by bicolored legs and completely black halteres

• predatory larvae
• bird nest associate
• boreal forest
• building inhabitant
• Palaearctic

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• The genome sequence of a window fly, Scenopinus jerei Pohjoismäki & Haarto, 2021 (Diptera: Scenopinidae).
• Scenopinusjerei, a new species of window fly (Diptera, Scenopinidae) from Finland.