Abstract
Within the Neuroptera order (net-winged insects), we find aquatic larvae in two families: lance lacewings (Osmylidae) and spongillaflies (Sisyridae).
Giant lancewing (Osmylus fulvicephalus) is only species within osmylids in the Czech Republic. The adults are diurnal or crepuscular weak-flying insects which mostly prey on small invertebrates, supplemented with some pollen. Eggs are deposited in damp places, usually near freshwater.
Adults have transparent spotted wings, tin antennae are short. They have two compound eyes, as well as three ocelli in between. Giant lancewing larvae have peculiar mouthparts which look like a thin forceps with the ends bending outwards. The body is elongated and slender and terminates in two extensible graspers bearing tiny hooks; these are used to aid in locomotion and to grasp prey. The larvae are associated with damp, mossy habitats and are amphibious. They hunt small invertebrate prey, from which they suck the body fluids with their mouthparts. Giant lancewing larvae are best collected by picking through mosses and stones along the margins of streams.
The forewings of adult spongillaflies (Sisyridae) have a span of 4-10 millimetres, their wings are greyish or brownish, folded like a roof. The sessile eggs of sisyrids are laid singly or in groups on objects that overhang water. Their water larvae have spindly legs, long antennae, and flexible, threadlike mouthparts. However, the second and third instars carry seven pairs of jointed, movable tracheal gills beneath their plump abdomen. Sisyrid larvae probe sponges with their long, flexible mouthparts. They are believed to feed exclusively on freshwater sponges, and they are unique among the Neuroptera in having segmented abdominal gills that function in breathing. After feeding and development, the mature larvae swim to the shore, attach to objects close to the water, and spin double-layered cocoons within which they pupate. Rearing Sisyridae larvae in the lab can be complicated due to the difficulty in keeping their sponge host and food source alive. Larval Sisyridae can be collected via a variety of methods, including picking them by hand from sponges, using benthic samplers in lotic habitats. This contribution describes the conditions for rather short-term rearing larvae of lance lacewings and spongillaflies and some ideas for experiments and observations in a school aquarium.