What Do Water Tigers Turn Into? Explained

Water tigers are quite famous for their large appetites and ruthless hunting abilities. But what do water tigers turn into when they grow up? Do they remain as voracious? Let’s find out.

When you find a new type of larva in your pool or backyard pond, it’s natural to wonder what it’s going to grow into and whether you should be concerned.

While water tigers are relatively harmless to us, you might be worried about them pupating into a dangerous or troublesome pest species.

Well, let’s dive in and find out what water tigers turn into.

What Do Water Tigers Turn Into

What Do Water Tigers Become?

Water tigers are the larvae of a beetle species known as the predaceous diving beetle. Their elongated bodies have long and thin legs that they use to swim and move around underwater.

Usually, the rear end of a water tiger floats on the surface while the remaining body remains suspended upside down.

Even in the larval stage of their life cycle, these insects are deadly predators. They suck out the juices of their prey using hollow pincers while grasping them within their powerful jaws.

They are voracious eaters and love to eat anything they can get their jaws on. They lurk around in the water, lying perfectly still, and attack when the prey least expects it.

Here’s a video of a water tiger attacking prey. Watch it to understand why they are so feared!


Predaceous Diving Beetles

This bug can grow between 1 to 1.5 inches long. You can find it in myriad colors, be it black, dark green, or olive, and it often has golden or other highlights.

Like many aquatic bugs, they have streamlined body that helps them move smoothly through the water.

What Do Water Tigers Turn Into

Unique Features

Although they are aquatic insects, predaceous water beetles are capable of flying too.

Underneath the upper pair of hard, shield-like wings known as the elytra, you can find another set of membranous wings.

The rear legs have a thick fringe of hairs that help them swim.

These bugs also possess short and powerful jaws with hollow teeth to bite their prey and inject enzymes that digest the prey from the inside out.


These diving beetles usually lay eggs on the leaves of aquatic plants, often by piercing into the stem.

The water tigers later hatch from these eggs and spend their larval stage in the water.

Once ready to pupate, they move out of the water and burrow themselves into the soil. Upon completing pupation, adult predaceous water beetles emerge.

The adult beetles live near or around water ponds and other sources of water and can also remain underwater for a long time.


Most of their life is spent in water, except for the pupal stage. They even lay eggs in water amidst the aquatic vegetation.

You will mostly find them in calm waters at the edge of ponds amidst weeds.

You may also come across predaceous water beetles in swimming pools and birdbaths, especially if there are electric lights to lure them.

Diving Beetle Larva

How Do They Survive Underwater?

Water tigers breathe underwater using spores near their abdomen, known as spiracles.

Adult beetles use the same spiracles to store oxygen so that they can breathe underwater, but their spiracles are under the elytra (wings).

However, the adults also need to breathe on land, so they don’t actually breathe underwater; they just use the spiracles to store oxygen.

Their respiratory system is quite complex and requires regular care. From time to time, they follow a process called secretion grooming to keep this critical system functioning properly.

In this process, they secrete a substance from their pygidial gland, which helps kill any harmful microbes in their spiracles.

By trapping air between their wings and body, they can carry extra breathable air while diving and stay underwater for longer. 

Some sources suggest they can stay submerged for more than a day! During the winter season, both the adult diving beetle and water tigers can be found under the ice.

What Do Water Tigers Eat?

One of the most notable details about water tigers is their feeding habit.

They earned their name from the fact that they are voracious eaters and powerful aquatic predators that even hunt prey larger than themselves.

Potential prey for water tigers in the wild include larvae of other insects, tadpoles, and even small fish.

Water tigers hunt by cautiously approaching their prey with their jaws wide open and snapping forward to seize them.

Grasping the prey in its jaws, the water tiger injects it with powerful digestive enzymes. The enzyme liquefies the prey from the inside out, and the larvae feed on this liquified food.

Water tigers can even hunt without eating the prey; if they see another attractive prey nearby, they will leave the other victim’s carcass lying around and go for the second hunt.

Despite being fierce predators, water tigers also have their own predators – such as fish, skunks, and raccoons.

Diving Beetle

Frequently Asked Questions

Are water tigers harmful?

Water tigers aren’t harmful to humans and usually keep to themselves. They might bite you if disturbed but won’t cause much pain or get you sick.

However, a large number of water tigers in your swimming pool might pose a problem.

Do water tigers bite?

Yes, water tigers have powerful jaws and can bite you if you get too close.

However, their bites aren’t painful to humans or spread any diseases. The same goes for the adult diving beetles too, but their jaws are more powerful, and the bites can sometimes draw blood.

Why is it called Water Tiger?

The larvae of the predaceous water beetle are called water tigers due to their voracious appetite and the way they hunt any available prey, even those larger than themselves.

As mentioned earlier, water tigers hunt a variety of aquatic organisms, including fish and tadpoles.

Where do water tigers live?

Water tigers mostly live on the edges of water bodies and prefer brackish water, which is why they are much more common in ponds than in swimming pools.

However, if the water in your swimming pool gets too dirty, it might attract these larval pests.

Wrapping Up

Water tigers and predaceous water beetles are mostly harmless; there’s nothing to worry about for humans. Some people even keep these diving beetles as pets.

However, if you find several of them in your swimming pool, it probably needs some shock chlorination to get rid of them.

Lastly, having them in your pond isn’t a bad thing as they can help eliminate mosquitoes by feeding on their larvae.

Thank you for reading; we hope you enjoyed this information!


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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8 thoughts on “What Do Water Tigers Turn Into? Explained”

  1. In England there is Dytiscus marginalis, the great diving beetle. Many years ago I kept one of the (really large, up to 60 mm) larvae of that species in an aquarium for a while. “Water tiger” is not an exaggeration; they are unbelievably ferocious. The jaws of that species are long and curved. The larva would attack anything whatsoever that moved near it, including a pencil. Supposedly people have been bitten. I certainly would not have volunteered to stick my finger in the tank!
    Susan J. Hewitt

  2. I agree that this is an aquatic beetle larvae but this looks more like a Water Scavenger Beetle (Hydrophilidae) larvae. Dytiscidae larvae have well segmented bodies (segments are very distinctive), legs are longer and jaws are longer and narrower but this larvae has short legs, sluggish type body (segments are hard to see) and the jaws are short and wide.

  3. I had a small tank of tadpoles several years ago, and caught a very similar larva in filling the tank with pond-water. It didn’t take very long for just a single larva to completely erradicate my poor tadpoles, it certainly was an impressive display of micro predation.

  4. Beware of these, if you keep fish tanks. One or two hitchhiked into one of my tanks, hidden within some native pond plants (that I had purchased in a fish store) – and killed most of the fish within hours (until I figured out what was happening, hunted them down and got rid of them).

  5. I found one today crossing a gravel road from one water filled ditch to the other. About 2 inches long. I took a clear picture. It can move very fast on land. Manitoba, Canada


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