Insect guide > Bugs > Water Scorpions

Water Scorpions

(Family Nepidae.)
The Nepids have been called "water scorpions" because their fore legs are swollen and fitted for grasping, and rather distantly resemble the cheliceres of a scorpion. The anal end of the body bears two long half-tubes which, when united, form a tube to convey air to the insect when the rest of the body is under water.

The water scorpions are either flat and oval or they are long and thin. Those of the former shape belong to the genus Nepa, and of the latter to the genus Ranatra.

As with the water boatmen and the back swimmers, these insects are predatory, and a large share of their food is the eggs of fish, but they also attack small fish and other water insects.

The eggs are laid in the stems of plants in much the same manner as are those of the back swimmers, but the egg itself is pushed entirely within the slit made in the plant by the insects' ovipositor, while there protrude several long filaments (seven in Nepa and two in Ranatra) which are supposed to be pneumatic in function.