Dragonfly Nymphs: The Underwater Predators Behind the Wings

When you watch a dragonfly skim across a pond, you’re seeing only the final chapter of its life. Before it had wings, it lived underwater—a six-legged predator with a grasping lower lip, internal gills, and a surprisingly effective escape system.

This aquatic youngster is called a nymph, the immature stage of an insect that develops into an adult without passing through a pupal stage. Dragonfly nymphs look so unlike their airborne adult selves that you could easily mistake them for an entirely different animal.

Here are five remarkable features of their hidden underwater lives.

1. Their Lower Lip Is a Prey-Catching Tool

Imagine being able to reach out and seize your dinner with your lower lip. That is roughly what a dragonfly nymph does.

Its specialized lower lip, called the labium, normally sits folded beneath the head. When prey comes within reach, the nymph rapidly extends it. Grasping structures at the tip catch the target, and the labium retracts, bringing the meal back to the mouth.

A grabber, not a tongue

Although this action might remind you of a frog flicking out its tongue, the equipment is quite different. The labium is a hinged mouthpart, not a tongue, and it physically grasps prey rather than simply sticking to it.

The sequence is straightforward:

1. The nymph gets close to prey—or waits for prey to approach.
2. Its folded labium shoots forward.
3. The tip catches the prey.
4. The labium draws the catch back to the jaws.

This reach means the nymph does not have to bring its whole body right up against its victim before striking. A creature that appears to be sitting quietly on the pond bottom may actually be waiting for the right moment to launch its grabber.

2. They Breathe Through Their Rear Ends—and Use the Same System to Escape

It sounds like a joke, but it is a fair shorthand: dragonfly nymphs take in water through the rear of the body to breathe.

Like other aquatic animals, they need access to dissolved oxygen—oxygen present in the water. They obtain it using gills, thin structures that allow oxygen to pass from the surrounding water into the body.

The unusual part is where those gills are located.

Why put gills there?

A dragonfly nymph’s gills sit inside a chamber in its rectum, the rear portion of the digestive tract. The nymph draws water into that chamber and pumps it out again, keeping water moving over the gills.

Breathing underwater is not about using the water itself as oxygen. It is about extracting the oxygen dissolved in it.

As oxygen is absorbed, the water around the gills needs to be replaced. Pumping supplies fresh water, much as moving air in and out of your lungs renews your oxygen supply—although the structures involved are very different.

This explains how the arrangement works. It does not mean the animal deliberately “chose” that location; it is an inherited feature shaped by evolution.

A built-in water jet

The same water-pumping arrangement has another use. By expelling water forcefully, the nymph can propel itself through the water.

Think of a water-filled squeeze bottle: push water out in one direction, and the bottle is pushed the other way. A dragonfly nymph uses that same basic principle for jet propulsion, helping it escape danger.

One system therefore supports two very different needs: taking in oxygen and making a rapid getaway.

3. They Are Serious Predators, Not Peaceful Pond Grazers

Despite being immature insects, dragonfly nymphs are capable hunters. Their diet depends on their size, species, and the prey available.

Possible meals include:

• Aquatic insect larvae, the immature forms of other insects.
• Other small aquatic animals.
• Tadpoles, when small enough to capture.
• Occasionally, small fish.

That last item can be especially surprising. We often picture fish eating insects, but the relationship can run the other way when a sufficiently large dragonfly nymph encounters a sufficiently small fish.

The important qualification is size. Not every nymph can tackle a tadpole or fish, and those animals are not necessarily its main food. For many nymphs, smaller invertebrates—animals without backbones—make up much of the menu.

If you look into a pond and see only stillness, remember that plenty of hunting may be happening among the plants and bottom debris.

4. Most of Their Lives May Pass Before They Ever Fly

The winged dragonfly is the conspicuous stage, but it is often the shorter one.

Depending on the species and conditions, the nymph stage can last months or years. The adult stage often lasts only weeks, although lifespans vary.

That changes how you might think about a dragonfly. It is not simply a flying insect with a brief underwater beginning. In many cases, it is an animal whose life is mostly aquatic, followed by a comparatively short aerial chapter.

5. They Become Adults Without a Cocoon

Dragonflies do not transform inside a cocoon. Their development is called incomplete metamorphosis: they grow through immature stages and then become adults without an intervening pupa, the stage familiar from a butterfly’s chrysalis.

When ready for its final transformation, a nymph climbs out of the water, often onto a plant stem, rock, or another support. Its outer covering splits, and the adult dragonfly emerges.

The new adult then expands its wings and allows its body and wings to firm up before flying.

The clue left behind

The empty nymphal shell is called an exuvia; more than one are exuviae. You may find one still gripping a reed or other surface beside a pond.

It is not a dead dragonfly. It is the discarded outer covering left after emergence.

Look closely next time you visit the water’s edge. A delicate flying dragonfly is impressive, but an empty shell on a stem tells an equally remarkable story: an underwater hunter has just become an aerial one.