What Eats Water Tigers (Diving Beetle Larva)? Hunting The Hunters

Water tigers are known to be hungry eaters who will bite and pierce anything that comes near them. But on the other end, what eats water tigers? Let’s find out.

Water tigers are the larvae of predaceous diving beetles, also known as Dytiscidae. Adult diving beetles usually have oval bodies, and the color can vary from black and dark brown to olive with a bit of gold.

The larvae have a reputation for being voracious eaters, using their powerful mandibles to tear apart any and every food item they can find.

You may be surprised to know, but these are one of the few aquatic insects found all over the world. There are nearly 4,300 species of these bugs.

What Are Water Tigers?

Water tigers are the larvae of a family of diving beetles that you will find in many freshwater ponds or similar habitats that don’t have fish (we will explain why later).

You can find these bugs in ponds and rock pools, but you might also come across some species in brackish water or even among leaf litter.

Predaceous diving beetles lay eggs in water, usually on aquatic plants. When the larvae hatch, they are about 0.5 to 2 inches in size.

Water tigers are shaped like crescents and have six hair-like legs coming out from their abdomens. They also have a long tails. They have a squarish and flat head and pincers in the front.

Water tigers mature slowly in the water till they come out and onto holes on the shoreline.

This is where they pupate, preferring the damp conditions rather than being submerged in

What Eats Water Tigers?

Water tigers are eaten by amphibians, skunks, and raccoons. But fishes feed on water tigers the most.

This is why you will find that water tigers occur in more numbers in ponds that don’t fish.

This is why water tigers are often limited to habitats near the shoreline to stay away from fish.

In a freshwater habitat, prey selectivity often determines the status of the water tiger, as they themselves can be predators.

Some adult water tigers are also considered edible. In several places around the world, there is a culture of eating various insects.

Varieties of adult water tigers are consumed in parts of Mexico and in regions across Japan, China, and Thailand.

However, these water tigers don’t have a lot of meat and can be a bit tasteless.

Adult diving beetles are often eaten by birds and reptiles. Usually, birds like herons tend to peck at them when they are on the surface of the water.

What Do Water Tigers Eat?

Water tigers are carnivores and are voracious feeders. They are stealthy predators that lurk and wait for their prey.

These larvae prey mostly on tadpoles, small fishes, mosquito larvae, leeches, and glass worms. They hunt by clinging to a piece of driftwood or grass in the water and then attacking an unsuspecting prey suddenly (like a tiger)

Water tigers wait without moving. As soon as the prey swims by, they use their strong mandibles to grab the prey and then inject digestive enzymes into it. This helps to kill the prey and turns its insides into liquid.

How Many Eyes Do Water Tigers Have?

You may wonder what makes the water tigers great predators. Interestingly, it is their complex visual system. The adult water tiger has arthropod compound eyes.

But, the larvae develop stemmata. These are not compound but simple lens eyes. The water tiger will have six stemmata on each side of the head, as well as a lens-less eye patch.

Each of the eyes has two different retinas, one on top of the other. This makes a total of fourteen eyes and twenty-eight retinas.

Since the predaceous diving beetle has such an elaborate visual system, its optical properties too are equally complex. But, the eyes that look forward are usually those that help them seek out the prey.

Frequently Asked Questions

Can diving beetles swim?

Diving beetles are great swimmers. They can live on and underwater for a long time. They can store oxygen in their bodies when they are going underwater.

Water tigers can also store air in breathing pores on the top of their abdomen. Water tigers live entirely underwater.

How do I keep diving beetles out of my pool?

To keep diving beetles out of your pool, you need to keep the pool clean. Since pools have fresh water, they may attract diving beetles if there are weeds that have small insects living in them. Once you clean it, you can also opt for chlorine treatment.

Can diving beetles bite?

Yes, diving beetles can bite, and even water tigers can do it. Water tigers have strong pincers that they use to grab onto anything they think is edible. They can bite humans as well.

The bite of these diving beetles can be a bit painful. However, they are not poisonous or venomous, so while they might hurt, they won’t cause any lasting problems.

Can water bugs live in chlorine?

Chlorine treatments are usually effective in getting rid of water bugs. If you have insects like water tigers and other bugs in your pool, you can opt for a chlorine shock.

Shock chlorination also helps to prevent algae, thus creating unsuitable living conditions for water bugs.

Wrap Up

The Dytiscidae has been the subject of much research. While diving beetles are mostly seen in the wild, a lone beetle can be a great pet as well. However, these bugs don’t live very long.

One interesting fact about these bugs is that they are captured by young girls in East Africa because their bite is supposed to stimulate breast growth!

We hope you found this article interesting, and thank you for taking the time to read it.

Reader Emails

Diving Beetle larvae are unique and fascinating creatures. Over the years, we have received several pics and experiences of our readers having either a good or bad time observing these bugs in the water.

Here are a few mails from the past so that you can decide for yourself!

Letter 1 – Water Tiger: Predaceous Diving Beetle Larva (and you can eat it!!!)

 

Killer bug!
Hi all,
I caught this little guy while trolling ditches for inverts for my naturalized tank at work. He was about 2.5″ long and particularily vicious. He killed virtually ever other invert in the tank, stole food from the 9 shiners and 1 “wild-caught” koi and the small frog and generally made a demon of himself. I think it’s a hellgrammite? Or some kind of stone nymph. Anyhow, the tank overheated one weekend during a power failure and i lost killer bug and my frog. 🙁 Keep up the good work! Cheers,
alicia,
Vancouver, BC

Hi Alicia,
This is a Water Tiger, the larva of a Predaceous Diving Beetle. There is an interesting description on a website known as Findarticles. We are sorry to hear about you stewing your local fauna tank. It sounds like a refreshing change for the usual jobsite aquarium. We once kept a Los Angeles River aquarium going for five years. Though the winged insects flew away, the three mosquito fish produced many generations until they finally succumbed to a rogue raccoon. We kept the aquarium outside on the patio.

Update: (11/04/2007) edible: water tigers
Hi Daniel and Lisa Anne,
I hope you both had a good trip to D.C. Both larval and adult predatory/scavenging water beetles are eaten in China and Southeastern Asia. A batch of adult Water Beetles were collected for me in Louisiana this past summer; I hope to receive them soon. They were gathered with light traps that some insect-hunters used; swarms of various insects came. I’m wondering if any of your readers know of people who collect insects this way, and if anyone has tried putting lights over the shallows of a pond to attract larvae and other water insects. If so I’d love to learn about their experiences. Best,
Dave Gracer
www.slshrimp.com/

Letter 2 – Water Tigers from Australia

 

Subject: Swimming pool bug
Location: Canberra Australia
October 22, 2015 9:58 pm
Hi Bugman.
I left my above ground swimming pool uncovered for approx. 6 months over winter. I didnt clean it nor did I add any chlorine. Now that its getting warmer I thought time to clean it out and start getting it healthy again. When doing so I caught 11 of these swimming bugs and I just needed to know more.
They swim to the water surface and sit there facing downwards (with the backsides toward the top).
When I stir the water they dive to the bottom (approx. 600mm) where I can’t see due to the leaves and other garbage – then do not come up for at least 5 minutes.
They appear to have 6 legs, two tails (split) and two clippers or claws on their face. They are very good at staying absolutely still, but when they swim they have a fish like turning movement. It should be noted that when I pulled them out of the water, they had no troubles walking around, moving almost like a scorpion.
I have attached a video and some pics.
This is in Canberra, Australia. Currently October (middle of spring) and heading towards summer.
Appreciate if you had any ideas on what these are?
Signature: thank you

These are Water Tigers, the aquatic larvae of Predaceous Diving Beetles in the family Dytiscidae.  There is a nice simple explanation of the life cycle of the Predaceous Diving Beetles on the Australian Museum website where it states:  “Larvae have a siphon (like a snorkel) coming out the end of their body. They stick this siphon out of the water to get oxygen to breathe.”  According to the Missouri Department of Conservation site:  “Larvae, called ‘water tigers,’ are elongated, flattened and can be 2 inches long. They commonly come to the surface to draw air into spiracles (like snorkels) located at the hind end of the body. There are 3 pairs of legs, and the jaws are strong pincers that are used to grasp prey.”  The Natural History of Orange County, California site has some nice images of Water Tigers.  As you can tell by our links, Predaceous Diving Beetles are found in many places on the globe.

Letter 3 – Green Heron eats Water Tiger

 

Subject: aquatic nymph as prey?
Location: Alexandria, VA
July 30, 2016 5:18 pm
Hi, I observed and photographed a Green Heron capture what I think might be a dragonfly naiad or some other aquatic nymph today at Huntley Meadows in Alexandria, Virginia. I wouldn’t expect a species ID, but do you think this is even an insect? I can’t think of another possibility…. Thanks!
Signature: Seth

Dear Seth,
What marvelous images you have submitted.  This larva appears to be a Water Tiger, the predatory, aquatic larva of a Predaceous Diving Beetle in the genus Dytiscus.  This posting is a marvelous addition to our Food Chain tag.