Small to medium sized larvae, to 4.5 mm. Head small, on swollen pale body. Likely parasitic on pupal caddis flies. Dorsal sclerite of head forming a clypeus, with apodeme separating from frons.
With 6 segments, segment 1 squat, bearing 1, possibly 2, setae and without Ring Organ; segment 2 divided by hyaline section, apex of 3 with peg sensillum (indicating its homology as apex of true 2nd); segments 3-6 decreasing successively in length such that apical is minute. Blade short and squat not extending to apex of segment 3, without accessory blade. Peg sensillum shorter than segment 4. Lauterborn organs absent.
Labral area compact: all S setae simple. SII well-developed, arising from pedestals; labral rod appears present. Pecten epipharyngis of 5 subequal lamellae; chaetulae absent. Premandible absent.
With well developed dorsal subapical tooth, large apical and 3-4 inner teeth, innermost pair including flat tooth and innermost merging into indistinct from mola. Seta subdentalis dorsally inserted, lanceolate, extending towards dorsal tooth. Seta interna 4 branched, each with slight indication of marginal feathering.
With single median tooth and 5 laterals even in size except outermost slightly larger, and acutely pointed. Ventromental plates essentially absent. Setae submenti retracted.
Broad, with few sensillae. Palp relatively well developed.
With few short setae at most. Anterior parapods strongly reduced, with few claws. Posterior parapods short, projecting laterally from body, each with c. 22 claws and 5 setae around parapod margin. With 6 weakly developed, short anal setae. Three pairs of large swollen anal tubules.
Erection of the subfamily Buchonomyiinae for the genus Buchonomyia has been controversial (see Cranston (1994) for summary). Robust molecular evidence indicates that it is the extant sister group to all other extant Chironomidae. From this phylogeny, the lack of premandibles is plesiomorphic, and eliminates relationships to Chironomoinea. The reduction / loss of procerci separates from all other non-Chironomoinea. The description of a 3rd instar larva by Ashe (1995) actually refers to a 4th instar, as revealed by a pharate larva of near identical morphometric measurements.
Three species of Buchonomyia are known, one from Burma, one (B. thienemanni) from Austria, Belgium, England, Germany, Ireland, Italy, Luxembourg, Slovakia, Spain and Iran (Brundin and Sæther, 1978; Marziali et al., 2004; Murray and Ashe 1981b), and a third from Costa Rica. Pupal exuviae have been obtained from clean, stony rivers. One (of two known larvae) was found within a pupal caddis case in western Ireland (Ashe, 1995) and more recently, from Austria a larva containing a pharate pupa.