Why are there so many dragonflies in my yard?

Dragonflies are some of the most fascinating insects in the United States. Despite their ferocious name and brightly colored exoskeletons, these flying insects are far less dangerous than you may first believe.

But what happens when dragonflies show up around your property in massive numbers? The sound of beating dragonfly wings or relentless hungry swarms could put your teeth on edge while in the yard or garden.

The short answer: they are feeding. A sudden swarm means something dragonflies eat has hatched nearby — usually midges or mosquitoes coming off standing water within a few hundred yards. Below is what dragonflies are, why they gather, what a swarm is actually telling you about your yard, and how to encourage or discourage them.

What are dragonflies?

Dragonflies are flying insects from the order Odonata. Approximately 3,000 dragonfly species are located worldwide, with an estimated 300 in the US and Canada. Although dragonflies share some resemblance to their close cousin, the damselfly, they are far better fliers and much heavier in build compared to these smaller insects.

There are several species of dragonfly common to the US, including:

• Green darner
• Migrant hawker
• Common sanddragon
• Great blue skimmer
• Midland clubtail

Dragonflies are primarily beneficial insects that consume other pests during their lifecycle. In fact, many gardeners strive to retain dragonflies for their many pest control proclivities. These insects cannot harm plants, people, or pets and prefer to live outside near stagnant water. Only one dragonfly species, the bee butcher, poses a significant risk to farming operations.

Since dragonflies are highly territorial in nature, you’re unlikely to see large numbers around your home. However, if you do have a high population of dragonflies in your yard, you may be dealing with a dragonfly swarm.

What are dragonfly swarms?

A dragonfly swarm is exactly what it sounds like: large groups of dragonflies circling about the yard or garden. Although they typically appear in spring and summer, they may also be present in early fall (if you live in a warmer climate).

You’re likely to spot dragonfly swarms near:

• Small ponds
• Water lilies
• Other bodies of standing water

Keep in mind dragonflies prefer to gather where prey species are prevalent. For example, you’re highly likely to find a static swarm around a pond filled with mosquitoes.

The reason dragonflies swarm is primarily due to warmer weather conditions. Other seasonal fluctuations (like periods of heavy rain) may attract large swarms in force.

A few other reasons you may have dragonfly swarms on your property include:

• Mass hatching and maturation. Dragonflies spend anywhere from a few weeks to a few years in the larval stage. Depending on when dragonfly adults last visited your property, you may experience the development of many adult insects all at once.
• The movement of prey species. Dragonflies are all-too familiar with the seasonal emergence of their favorite foods, including flies, ants, and mosquitoes. They won’t hesitate to live in places with good water proximity in the hopes of catching an easy meal.
• Migratory swarms. Many species of dragonfly, including the green darner, travel long distances for up to three generations to ensure the survival of their species. If you’re lucky, you may catch a migratory swarm moving into your yard as the insects follow their migration path.

Large dragonfly gatherings are typically rare and do not pose a problem to humans. In fact, spotting one around your yard could lead to some long-term benefits for your garden. Not only do these insects eat other insects while in their larval phase, but static swarms could head off future infestations by eating adult pests such as mosquitoes and other small insects.

But perhaps you don’t have any dragonfly swarms near your property. In that case, you may be interested in finding some ways to encourage the adults to drop by.

Attracting dragonflies to your property

What attracts dragonflies to properties quickly? All you need is some standing water and a green thumb.

Here’s what you need to know:

• Make your property a haven for small insects and other prey species that attract dragonflies. Remember: dragonflies can consume small fish, water bugs, and even larger insects like beetles and bees. Encouraging biodiversity around your property is a great way to attract dragonflies quickly.
• Be cautious about where you hang bird houses and suet feeders around your yard. Larger birds are all-too happy to snap up large insects like dragonflies, which could make it difficult for these brightly colored insects to maintain a presence in your yard.
• Any body of standing water can attract dragonflies to your home. Setting up a koi pond is just one example of a water body, although you can also set up less complex areas by putting a few border stones around a vernal pool.
• Try putting dragonfly-friendly plants around the front and sides of your home. You can draw dragonflies closer with Joe-Pye weed or Black-eyed Susans, or plant some water lilies in standing water to retain nearby static swarms.

How to control dragonflies flying around your yard

A dragonfly swarm isn’t dangerous — but that doesn’t mean you want one around your property. If you’re looking to reduce the numbers, here’s what tends to work:

• Set up plenty of bird feeders around your yard and garden. Next, try introducing tadpoles and bat boxes to your yard. Adult stage dragonflies are a favorite food of small birds and bats, while nymphs are beloved by frogs, newts, and lizards.
• Mow your grass at least once a week to keep the height under four inches. Turn off your sprinklers as well, to stop other insects settling in and attracting hungry dragonflies.
• Organize, stack, or clear any clutter around your property. Rotting wood or decaying leaves in ponds could be some of the biggest reasons dragonflies visit your home. If you live in a warmer climate, consider getting rid of excess brush to prevent termites, carpenter ants, and other wood-destroying pests from attracting dragonflies (and damaging your home).
• Deal with the food source rather than the dragonflies. Controlling the mosquitoes and flies they are feeding on is the only approach that actually holds.

The dragonflies are not the problem — the hatch is

This is worth saying plainly, because it changes what you should actually do. A sudden swarm is a feeding response. Dragonflies arrive in numbers because something they eat arrived in numbers first, usually midges or mosquitoes emerging from standing water within a few hundred yards.

So killing the dragonflies would be both difficult and backwards. They are among the most effective mosquito predators you can have on a property. Remove the hatch and the swarm moves on by itself within a few days.

The question worth asking is where the water is. Check the obvious pond, then check the things people miss: a gutter run holding water because it has fallen out of pitch, a sagging tarp or trampoline cover, saucers under plant pots, a corrugated downspout extension, an upturned wheelbarrow, a tyre swing, a bird bath nobody has emptied. A mosquito generation needs about a week and roughly a bottle cap of standing water — the source is usually far smaller and closer than people expect.

Find it and tip it out and you have solved the whole thing yourself. There is nothing else to do and nobody to call.

Where it stops being a job you can finish is when the swarms return season after season and there is no standing water anywhere on your own property. At that point the breeding site is somewhere you cannot reach — a neighbouring lot, a storm drain, a ditch or a low area that holds water for a week after every rain. That is a habitat problem rather than a spray problem, and it is the one situation here where professional mosquito control is worth the money, because the work is finding and treating breeding sites rather than fogging your garden.

Dragonfly FAQs

Now you know the answer to ‘why are there so many dragonflies in my yard?’ However, you may still have a few questions related to their control, migration, and habitat areas.

Let’s take a look at some common dragonfly FAQs sourced from an aquatic entomologist.

Is it good to have a lot of dragonflies in your yard?

Dragonflies cannot damage fruits, vegetables, and plants and act as natural pest control in your yard. Although they can bite humans if captured or threatened, they are not naturally aggressive and rarely choose to attack.

If you’re a backyard gardener looking to get rid of pests in the yard safely, large swarms of dragonflies may actually be a good thing. You can easily control many insects and their young without relying on harsh chemicals.

What does a swarm of dragonflies mean?

Dragonfly swarms usually stem from your yard, your climate, or passing migratory swarms. These insects may stick around for feeding purposes before moving to a new area or appear each year in the summer when the weather warms up.

Remember that a large influx of dragonflies could point to a secondary pest infestation, as swarms gather to feed on common prey insects like mosquitoes, flies, moths, and bloodworms.

Why are there so many dragonflies this time of year?

Dragonflies love warmer weather and typically appear in force during the spring and summer months. This coincides with the rise of other insects, including some of their favorite snacks.

However, keep in mind that dragonflies can appear anywhere their ideal environment is located. This may include a large body of water, a small pond, or a marshy area with plenty of shade and sunshine.

What does it mean when you see dragonflies?

Spotting a lot of dragonflies near your property could mean one of three things.

First, there may be a migratory swarm moving through your area that temporarily settled down in your yard.

Second, static swarms appearing in early spring may indicate large numbers of hatching and maturing bugs.

Third, a smaller group of dragonflies flying near your pond or mown grass could indicate seasonal feeding on a specific pest, such as a heavy mosquito hatch.