Back swimmers (family Notonectidae) actually swim upside down. They live in fresh water, where they hunt insects, fry and tadpoles and suck out the intestines with their short, strong proboscis. If water bugs are squeezed or get in contact with a human body during bathing, they may bite. Back swimmers’ bites are painful.

Common backswimmer	Saucer bug	Water scorpion

Creeping water bugs, Naucoris cimicoides are another example of water bugs, which normally use the proboscis to suck out the intestines of their prey – and which also inflict painful bites to humans.

Fig. 26. Biting water bugs live in still water. (Ib Andersen)

The water scorpion, Nepa cinerea, lives in shallow ponds and lakes where it crawls around on water plants. It sits in wait and grabs its prey with its first pair of legs, which are converted to hooks which are reminiscent of a scorpion’s pincers.

Water scorpions have a long breathing tube which forms a respiratory tail. It uses the breathing tube to stay connected to the surface of the water. It looks like a sting but it can not sting with it. It can, however, like other water bugs, bite with its proboscis.