What Dragonflies Eat and What Eats Them
The Ultimate Aerial Hunter is Not Without Its Own Hunters
Aug 12, 2009
The order Odonata that encompasses the dragonflies and damselflies is named for the teeth these animals use for eating their food. Although young and adult dragonflies and damselflies are exquisitely equipped for hunting, capturing, and eating insects, they in turn are hunted and eaten – sometimes by the same organisms they feed on.
Larval Predation
Larval odonates feed on a varying suite of prey as they grow. Newly hatched larvae eat microscopic zooplankton: copepods, crustaceans, and early life stages of aquatic insects. Medium sized larvae attack the larvae of mosquitoes, midges, blackflies, small worms, tubifex worms, and other small aquatic denizens. Large larvae focus on larger worms and nymphs of aquatic insects, tadpoles, the fry of fish, and even other odonate larvae.
The hinged lower jaws of odonate larvae are elegant tools for capturing prey. A camouflaged or buried larva will wait for prey to move into range, shoot out its jaw to stab the prey in its vice-like toothed jaws, then almost as quickly retract the jaws and begin eating. Even with an offensive weapon like this, it is not difficult to overwhelm an odonate larva. Their bodies are easily punctured and crushed, allowing most larger animals to be able to capture larval odonates.
- Other odonate larvae: Dragonflies are not above eating their own kind or related species. They feed on the premise: “If it is smaller, and in range, eat it.”
- Water bugs and beetles: The adults of these voracious semi-aquatic predators are about the size of a baby turtle and attack anything that moves. Their larvae are also equipped with formidable pinching jaws, hide in vegetation and below rocks, and strike at anything that moves by. In an attack on or by one of these larvae, the larger of the two larvae usually wins.
- Hellgramites: The larval forms of aerial dobsonflies that, like the beetle larvae, have formidable jaws and hunt from ambush. These grow to almost 5 cm (2 inches), and the older ones find odonate larvae a delicacy.
- Frogs and fish: While these consumers gulp down any small insect, eating odonate larvae eliminates predators of their own tadpoles and fry – as well as nourishes their own bodies.
- Turtles, ducks, and other aquatic birds do not have young that are susceptible to being eaten by dragonflies, but they do consume both larvae and newly emerged adults when encountered.
Adult Predation
Dragonflies and damselflies are strict insect eaters. They are only equipped to handle small flying insects and some spiders. Not every nearby insect fits the bill, however. They do not take large numbers of hard-shelled beetles, and pass by the large-winged butterflies. Their primary prey are mosquitoes, flies, mayflies and dobson flies, other odonates, small moths and butterflies, and wasps and bees.
The array of organisms that eat adult dragonflies is as varied and includes many of the same species as the animals that eat their larvae.
- Fish and frogs take many odonates close to the water. Females ovopositing on and near the water surface are especially vulnerable.
- Aquatic birds and turtles eat fewer adults than they do nymphs and naiads, but metamorphosing larvae are consumed in large numbers.
- Songbirds including blackbirds, sparrows, flycatchers, kingbirds, grackles and jays consume many metamorphosing larvae, sometimes carrying several in their beaks in a manner similar to puffins carrying fish when there is a large hatch of dragonflies.
- The flycatchers, kingbirds, blackbirds team up with swifts, swallows and martins to feast on adult odonates. Purple martin (Progne subis) houses are set out with the misguided intent of having these birds eat large numbers of mosquitoes. Instead, they prefer to eat the damselflies and smaller dragonflies that would help reduce mosquito populations better if left alone.
- As many dragonflies and damselflies are active at dusk and dawn, bats, whippoorwills, and nighthawks are added to the list of vertebrate dragonfly predators. Although not as agile as the odonates, they fly faster and coming from the rear, are difficult to evade.
Spiders, large predatory wasps, and other dragonflies also take a toll on adult odonates. The group of dragonhunters feed primarily on other large dragonflies, while smaller dragonflies capture and eat damselflies. Large spiders construct webs capable of halting the largest dragonflies in mid flight, and smaller spiders capture the smaller dragonflies and damselflies. Predatory wasps fly in from behind, sting the dragonfly, and wait for it to drop from the sky before consuming it. Some attack the large darners while they rest. If they are not successful, the tables may be turned and the wasp becomes a meal for the odonate. One wasp stings dragonflies, flies them back to her nest, lays an egg on the live but paralyzed dragonfly, and lets the larva eat it.
Parasites
In addition to predatory insects and vertebrates, the nymphs of many species of mites attach to the larvae as they move out of the water to molt. Although a few mites are insignificant, heavy infestations can weaken or kill the dragonfly. These mites often feed on the dragonfly predators and leave a captured dragonfly to feed on their preferred final host to mature and reproduce.
As always in the natural world, it does not matter how strong, large, or dangerous an animal is – there are always others who can evade being eaten and attack even the most successful of predators.
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