First instar larvae of Polystoechotidae sp., and first and older instar larvae of Ithone fusca Newman and Oliarces clara Banks are described; those of the latter species for the first time. The family Ithonidae is unique in Neuroptera in having grub-like C-shaped older instar larvae. Potential morphological synapomorphies of mature larvae of Ithonidae and Polystoechotidae are the mandibles with exceptionally broad base and markedly thickened apical part; antennal curvature is fixed and rather characteristic in shape; ocular area reduced or absent; cardo and stipes are markedly enlarged with stipes much larger than the cardo; presence of gula (Polystoechotes) or some traces of gular sclerotisation (Ithone, Oliarces). Larvae of Ithone have numerous larval autapomorphies such as C-shaped first instar larva with reduced abdominal segments IX and X; fused tibia and tarsus on all legs and dorsally directed maxillae. Larvae of Ithonidae and Polystoechotidae have some similarities with those of the family Dilaridae, such as no or one pair of stemmata; body not flattened dorso-laterally; mesothoracic spiracle located on fold between prothorax and mesothorax; short and stout mandibles widened at base and tapered apically; robust and elongated fore legs; tarsi on all legs markedly shortened; more than three larval instars. Older instar larvae of Ithonidae are markedly similar to those of the beetle superfamily Scarabaeoidea in having a C-shaped body, at least in older instars; body round in cross-section; sclerites on thorax and abdomen reduced and body surface membranous; each thoracic and abdominal segment subdivided dorsally into two or three fleshy lobes; ventral surface of abdominal apex bears a field of short and stout setae. Chaetotaxy pattern in first instar Ithonidae and Polystoechotidae larvae suggests that it is possible to homologise the sensilla in different genera and provide a system of sensilla designation for Neuroptera larvae. This study is illustrated with 36 morphological drawings.