Small to medium-sized larvae.
Antenna slightly longer than 1/2 length of mandible; 5 segmented; segment 4 slightly longer than third. Blade nearly as long as flagellum. Lauterborn organs present, as long as 3rd segment. Style present, as long as 3rd segment.
SI serrate with 5-7 branches, other S setae simple. 1 chaeta plumose, remainder numerous and simple. Pecten epipharyngis of 3 rounded scales, chaetulae laterales of simple elongate scales, and plumose setae. Premandible with 2 apical and 2 broad inner teeth, without brush.
Apical tooth shorter than combined width of 4 inner teeth. Seta subdentalis extends to innermost tooth. Seta interna with few plumose branches.
Mentum with 2 median teeth higher than 1st pair of lateral teeth; 5 pairs of lateral teeth on evenly decreasing slope. Base of mentum with rounded tooth-like development on posterior of otherwise small ventromental plate; without beard.
Maxilla palp normally developed.
Body with anterior and posterior parapods divided, bearing claws. Procercus squat, as high as wide, bearing 6-7 anal setae. Supra-anal seta about 1/3 length of anal seta. Anal tubule length unknown. Body setae simple and short.
Larval Compterosmittia are little known, with a single example reared from the contents of a Nepenthes pitcher plant from Hong Kong. A second unreared species is reported from the axils of Richea pandaniformis in Tasmania, Australia (Cranston and Kitching, 1995). Adults show a distribution from Caribbean, Appalachians (eastern North America), Japan, and there are several Micronesian species described of uncertain status.