Relatively large larvae, up to 9.1 mm long. Coloration blood red.
Antenna with 6 consecutively smaller segments; segment 6 vestigial. Blade nearly as long as flagellum. Lauterborn organs small but dark colored and distinct; may appear as a very short segment 3.
Labrum with SI finely plumose. Labral lamella simple, triangular, weakly sclerotized. Chaetae somewhat reduced in size and number. Pecten epipharyngis consisting of 3 simple, sclerotized, smooth, and sharply pointed spines. 6-7 pairs of chaetulae laterales present, all smooth. Premandible with 2 apical teeth and distinct inner tooth; brush absent.
Mandible with apical tooth much shorter than combined with of 3 inner teeth. Seta subdentalis apically indented. Seta interna with 6-7 smooth or weakly serrated branches.
Mentum with 2 median and 6 pairs of lateral teeth; median teeth lower than first lateral teeth. Ventromental plate well developed; beard absent.
Maxilla with anterior lacinial chaeta low and broad with 5-7 apical spines. Lamellae of galea unserrated. Pecten galearis well developed.
Body with procercus well developed, strongly sclerotized, particularly posteriorly; with 6-7 anal setae. Supraanal seta strong, more than 1/2 as long as anal setae. Anal tubules much shorter than posterior parapods. Body setae not conspicuous, although the longest may reach 1/4 segment length.
Larvae of Trissocladius are very similar to those of Hydrobaenus, distinguished only by the lower median mental teeth of Trissocladius.
The larvae live in temporary and permanent puddles where they build loose tunnels of mud and plant remains. Adults emerge in spring. The few species are known from western Europe and 1 from North America.