Family Xylophagidae

Vertex flush with eyes or slightly depressed, eyes widely separated in both sexes, antennal flagellum with an apical arista, or with 8 or 20-36 flagellomeres, pectinate, subpectinate, or serrate, clypeus recessed in a deep facial groove and flattened, in profile with anterior surface depressed below level of parafacial, and not reaching dorsally to bases of antennae

Scutellum usually unarmed, large, convex with a hairy disc, evenly rounded apically, subscutellum absent or very weakly developed; posterior thoracic spiracle never with a scale-like elevation immediately behind it

Legs slender, tibial spur formula 1-2-2, fore tibia with a ventral apical spur, precoxal bridge absent, empodia pulvilliform

Wings always present, C either extending to slightly beyond wing apex, or, as in most taxa, continued around the wing, branches of R and M diverging to apical wing margin, branches of M joining margin well below apex of wing, without a composite ‘diagonal vein’, branches of R not crowded anteriorly, Rs arising well before base of cell d, R2+3 ending at C near R1, R5 ending at or beyond wing apex, crossvein r-m close to base of cell d, cell d large, at least as close to posterior margin as to anterior margin of wing, at least 2 times as long as broad, M usually 3 branched, CuA, free or meeting A, in an acute angle near wing margin, anal lobe and alula well developed, calypters small