Tracheal-gills
Guides
Sisyridae
spongillaflies, spongeflies
Sisyridae, commonly known as spongillaflies or spongeflies, are a small family of aquatic Neuroptera with approximately 60 extant species worldwide. Adults are small, brownish or greyish insects resembling brown lacewings (Hemerobiidae), with forewings spanning 4–10 mm. The family is distinguished by their unique larval biology: larvae are aquatic and obligate predators of freshwater sponges (Porifera: Spongillidae) and bryozoans (Phylactolaemata), using elongated piercing-sucking mouthparts to extract cell contents. Larvae possess seven pairs of jointed, movable tracheal gills on the abdomen—a trait unique among extant insects. The family has a fossil record extending to the Late Cretaceous, with two extant subfamilies (Sisyrinae and Paradoxosisyrinae) and four living genera: Climacia, Sisyborina, Sisyra, and Sisyrina.