Water Scorpion

• GeneralIt breathes through a tail tube that breaks the surface like a snorkel.
• It swims very poorly: it prefers to walk along the bottom, and its dead-leaf appearance makes it all but invisible.
• It has wings folded beneath its wing cases, but most individuals never fly at all because their flight muscles are atrophied.
• It is no scorpion and it does not sting with its tail: what looks like a sting is a breathing siphon formed of two interlocking half-tubes, which it pushes up to the surface to breathe. The painful jab comes from the proboscis.
• It hunts by ambush: it stays motionless among the vegetation and seizes insect larvae, crustaceans, tadpoles and small fish with its raptorial front legs.
• It is one of the leading predators of mosquito larvae — Anopheles, Culex and Aedes — and is being studied as a biological control agent against disease vectors.
• The eggs, stuck upright into the substrate, carry five to eight respiratory horns that float free in the water; only the family Nepidae has them.
• The nymphs have no developed siphon and breathe through six pairs of abdominal spiracles.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Shallow bottoms of ponds, ditches and backwaters

Size at birth

Elliptical egg 1.3 mm wide by 1.63 mm long, with 5 to 8 respiratory horns at the anterior pole that float freely in the water

Gestation / incubation

The eggs, laid upright in submerged vegetation, hatch in 8-10 days according to one study and in 3 to 4 weeks according to British observations; five nymphal instars follow

Litter / clutch size

Around thirty eggs per female, attached to aquatic plants or algae

Sources consulted: Wikipedia (es): Nepa cinerea · Brickfields Country Park, ficha Water scorpion · Microscopy and Microanalysis (Oxford), estructura del huevo de Nepa cinerea · Aquatic Bugs · Aquatic Bugs, ficha Nepa cinerea · Datos morfometricos del genero Nepa · ficha de especie de Nepa cinerea

Best time: The adults overwinter and mate in April and May; the new adults appear around mid-August