Dragonflies in the garden: The hidden life of the hunters by the pond

Key points at a glance

• Dragonflies undergo a long developmental phase as predatory larvae underwater.
• Emerging on vertical structures like reed stems is essential for their metamorphosis.
• Finding exuviae (cast-off larval skins) is clear proof of successful reproduction at the pond.
• A structurally diverse garden pond with shallow water zones serves as both a nursery and a hunting ground.

The cycle beneath the water's surface

If you see more dragonflies patrolling your garden in July, they haven't suddenly migrated from afar. These creatures are the result of a years-long development that has mostly taken place hidden beneath the water's surface. As larvae, dragonflies live as predators, feeding on small aquatic organisms. Their presence in the pond is an indicator of a healthy, functioning ecosystem. Only once their biological development is complete do the larvae leave their aquatic environment to transform into the flying adult insect (imago).

Metamorphosis on the bank

The transformation process makes high demands on the quality of the habitat. The larva leaves the water using vertical structures such as rushes (Juncus) or reeds (Phragmites australis). This is where moulting takes place. The old skin, known as the exuvia, remains firmly anchored to the stem. As the insect is extremely vulnerable during emergence and the subsequent hardening phase, these bank areas must not be disturbed in midsummer.

Requirements for the water body

For dragonflies such as the Southern Hawker (Aeshna cyanea) or the Four-spotted Chaser (Libellula quadrimaculata) to use your garden as a habitat, the physical structure must be right. A pond with steep, smooth edges offers the larvae no way to climb out for emergence. Furthermore, fish pose a danger, as they view the predatory larvae as a food source.

Action plan for a dragonfly-friendly garden

1. Maintain structures: Do not cut back water or marsh plants at the pond edge in July, so as not to destroy the emergence sites.
2. Critically assess fish stocks: Avoid keeping fish in the pond to significantly increase the survival chances of dragonfly larvae.
3. Create natural banks: Create shallow, gravelly bank areas and plant native species such as the yellow iris (Iris pseudacorus).
4. Create hunting habitats: Promote the density of flying insects—which serve as food for young dragonflies during their maturation phase—by leaving areas of long grass and meadow edges.
5. Use observation: Look out for exuviae on the stems. They are biological proof that your pond is successfully serving as a breeding ground for dragonflies.

Frequently asked questions

Why do dragonflies suddenly appear in the garden in July?

The animals were already in the pond as larvae. They only emerge in midsummer, becoming visible as flying insects.

What is an exuvia?

An exuvia is the empty, cast-off larval skin that remains on plants or stones after the dragonfly has emerged.

Should fish live in a dragonfly pond?

No, fish eat dragonfly larvae. To maintain high insect diversity, you should avoid stocking the pond with fish.