Water Scorpions (Nepa cinerea) can be found all around the UK in ponds, lakes, shallow slow-flowing water and sometimes in stagnant water. They are also known as ‘toe biters’ because that is exactly what they do – they bite your toes! The bite is not poisonous but it can be painful so you may have to be careful when you are wading in shallow water. And here’s a tip, if you should happen to be looking at water and you think see a small dead leaf on the water’s surface, this could well be a Water Scorpion because this bug is flat and a blackish brown colour, just like the colour of dead leaves, and it keeps very still in water. You will know if it is a Water Scorpion though because it has a very long tail which it uses to breathe. It breathes by pushing its hollow tail up to the surface of the water and once it has enough oxygen it stays under water for about thirty minutes.
Even though Water Scorpions live in water they actually don’t like swimming so more often than not you will find them clinging onto water plants most of the time. Water Scorpions can also fly, but they don’t do that very often too because their wing muscles are often under developed. Fortunately for them they don’t need to fly that much to catch prey as they mainly feed on tadpoles, water worms, water fleas, insect larvae and sometimes small fish. Water Scorpions use their powerful front legs to catch their prey and then use their piercing and sucking mouth parts to suck the fluids out of each victim.
Water Scorpions have three pairs of legs and when they swim they move their front legs up and down and at the same time move their second and third pair of legs like rowing oars. They can look quite awkward when they are swimming. Sometimes Water Scorpions crawl on the ground in very shallow water so be careful where you stand otherwise you may get bitten!
Water Scorpions can make chirping sounds and the males usually do this when they want to attract a female. This sound is made by rubbing their legs against their body. Once a couple have found each other and mating has taken place, the female usually lays around thirty eggs on water plants or algae. The eggs have long hairs which can be seen floating freely on the water. These hairs allow the little ones to breathe inside the eggs. After about four weeks the little ones, called nymphs, hatch out and they all look very hairy indeed. Nymphs have to go through metamorphosis to become adults, which means they have to go through a series of moults. They moult five times and it takes around eight weeks before they turn into fully grown adults and then they could bite your toes too!