Water boatmen

With long legs to swim, the water boatman is a small creature found on the surface of our canals.

A small insect with red eyes and a striped yellow body.

Lesser water boatman

Water boatmen facts

Scientific name: Corixa punctata

Family: Corixidae

Diet: Algae and dead plant material

Predators: Fish, amphibians, birds and larger invertebrates, like dragonflies

Size: Up to 1.5cm

Lifespan: One year

About water boatmen

Lesser water boatmen are one of many water boatmen species in the UK. Lesser water boatmen are from the Corixidae family, while greater water boatmen (more commonly known as backswimmers) are from the Notonectidae family.

Male lesser water boatmen ‘sing’ like grasshoppers to attract mates. And if you’re quiet by our canals in summer, you may hear their song – especially at night.

Water boatmen and our canals

Water boatmen are widespread in freshwater habitats. They have long green hind legs to swim on top of the water (unlike the common backswimmer, who swims upside down) and are found in many canals, weedy ponds, lakes, and ditches. When the weather warms, adult water boatmen sometimes take flight to find new waters.

How to identify water boatmen

Ranging from green to dark brown with yellow stripes, water boatmen are difficult to tell apart from the similar common backswimmer – but lesser water boatmen do not swim upside down. They have powerful hind legs covered in tiny hairs which help them to swim on top of the water.

A buff-tailed bumblebee with two yellow bands and a white tail with buff markings feeds on pollen from a purple flower

Insects to find on your local canal

From bright butterflies to bees that burrow beneath, what can you spot?

What do water boatmen eat?

Water boatmen are herbivorous, filling up on algae and detritus. They also need to breathe at the water’s surface to survive spending large periods underwater and have evolved to collect oxygen from the surface and carry the air bubble on their back.

How do water boatmen breed?

Like plenty of aquatic insects, water boatmen start their lives as nymphs – small and translucent green. They undergo several moults before becoming adults. When mature, they lay their eggs underwater in the leaves of aquatic plants.

Where do water boatmen live?

Water boatmen are common in most open bodies of water, like our canals, reservoirs and lakes, as well as smaller freshwater habitats, like ponds and ditches.

Take a walk to spot insects

At Diamond Jubilee Wood, we've improved the pond for wildlife, including water boatmen

Tring Reservoir surrounded by green fields

Open water

Many of our open water habitat sites are protected areas because of their importance for wildlife

Tips to spot water boatmen

They may be small, but if you’re keen-eyed, you’ll see water boatmen and plenty of other aquatic insects on the surface of our canals. And if you can’t see them, you might be able to hear them.

Like grasshoppers and crickets, some male water boatmen can stridulate – meaning they rub parts of their bodies to produce sound. To hear their song, head to our canals on a summer’s evening and listen carefully.