Dragonflies and their nymphs are voracious predators. They hunt by sight, detecting prey by its movement. Nymphs need food to grow large enough to transform to adults. They don’t use a lot of energy foraging, so most of what they eat is converted into body tissues. Adults do not grow, but they must build up reserves for breeding. Dragonflies can double their weight as they pass from teneral to mature adult, growing larger flight muscles and storing fat. Adults convert some of their food to body tissues, and to eggs and sperm, but most is turned into energy for flight.

Do dragonflies drink? Adults get much of the water they need from the food they eat, but will drink from water surfaces or droplets of dew.

Small nymphs feed on tiny aquatic invertebrates. As they grow they eat larger invertebrates and even small fish and tadpoles. Most hunt by sight, but some use their antennae to feel movement. They aren’t picky about what they eat. If it moves and is about the size they think they can handle, they go for it!


Watch a nymph eat a worm.
(Video = 30 sec., 1.0 Mb)

 

Watch a higher resolution version of this video on YouTube. Click Here: Nymph Eating!


Labium in action, slow motion.

Nymphs catch prey with their labium, a modified lower lip that shoots out with lightning speed. The labium holds prey firmly as the jaws tear it apart. Nymphs of some species crawl through aquatic plants looking for prey. Others wait in ambush, lying hidden in mud or clinging to plants or rocks.

Most nymphs are green or brown to match the colour of aquatic plants or a mud bottom. They are camouflaged to hide from their prey AND their predators.

Dragonflies are aerial hunters that catch and eat other flying insects. Small prey can be caught directly in their jaws or they can use their spiny legs like a basket to snare insects. When larger prey is caught, dragonflies usually perch somewhere to eat it, but smaller prey can be eaten in flight.

Dragonflies are opportunistic hunters and will take whatever prey is available, but each species hunts in its own way. Some, like many Darners (Aeshnidae), spend much of each day flying, searching for food. Others spend more time perched, waiting for prey to fly by. Many Clubtails (Gomphidae) perch on the ground, while many Skimmers (Libelluidae) perch on low vegetation. Species will differ in the time of day when they hunt (daytime or dusk), where they hunt (forest, meadow or marsh) and what they hunt (large or small insects). Some, especially damselflies, will snatch insects off the ground or from vegetation.

Watch some dragonflies chowin' down!
(Video = 0:23, 0.7 Mb.)

Watch a higher resolution version of this video on YouTube. Click Here: Chowin' Down!

Most dragonflies hunt during the daytime, when it is sunny and warm. Most mosquitoes remain hidden in the daytime, so they’re not a major food item for most dragonflies. Nymphs will eat mosquito larvae, but most nymphs live in permanent water bodies, while mosquitoes breed mainly in temporary waters. Mosquitoes can have several generations in one summer, so their populations can rise dramatically in a short time. Dragonflies have only one generation each year, so their numbers cannot increase to match mosquito populations. Dragonflies are an important part of wetland ecosystems, but they can’t control mosquito numbers. In nature, the availability of prey usually limits predator populations, not the other way around.

 

Nymphs are eaten by many animals, including other aquatic insects, fish and turtles. They are eaten by other nymphs, too! Dragonflies are food for birds, frogs, spiders and other predatory insects. Mass emergences of dragonflies along lake or river shores can offer a banquet for predators. Large dragonflies often eat smaller dragonflies! People eat dragonflies, too. In some Asian cultures dragonflies are considered delicacies.

A common parasite of both adults and nymphs are water mites, tiny round relatives of ticks. Mites feed on the body fluids of nymphs, then transfer to the adult as it emerges and continue feeding.

 

The Dragonhunter (Hagenius brevistylis), our largest dragonfly species (10 cm body length), specializes in hunting large flying insects, and much of its diet ends up being other dragonflies!


1) Basic Biology

2) Life Cycle

3) Palaeobiology

4) Biodiversity

5) Biogeography

6) Overwintering / Migration

7) Food

8) Sight and Flight

9) Cultural Significance

10) Conservation

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