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Are Dragonflies Attracted to Light?

  • Animal
Are Dragonflies Attracted to Light

Yes — but only when it’s a certain kind of light. This is perhaps one of the strangest things about them. Dragonflies (family Syrphidae) have long been known for their habit of hovering over bright objects like streetlights or car headlights at night. It seems that these bugs can’t resist the lure of an unshielded lamp or other source of illumination, especially if it has some sort of moving object inside it.

In fact, this tendency may help explain how people first noticed them back around 200 B.C., since many sources report that early Greek soldiers used to attract large numbers of dragonflies by hanging lanterns above their heads as they slept.

But why would such a big insect find itself drawn to something so apparently benign? The answer lies with those three-pronged eyes on each side of its head, which are similar to what you might see on the compound eye of another group of creatures called “insect vision sensors.” These ocelli detect movement and directionality, much like our own retinas do. So while we know that dragonfly larvae spend time feeding under lamps, scientists aren’t exactly sure why adult flies act similarly.

Are dragonflies Sensitive to light?

Are dragonflies Sensitive to light

What researchers do understand is that there’s more than one reason why they’d be interested in light bulbs. For example, because dragonflies don’t fly during the day, they need to use sight to track down potential mates and hosts where there isn’t any sunlight.

They also rely heavily on seeing prey items up close while perched atop plants, shrubs and trees; without good nighttime vision, they could easily miss smaller animals hiding underneath leaves. Finally, the adults actually feed off of nectar from flowers, pollen grains and small aquatic animals, including mosquito larvae.

During summertime mating season, however, male dragonflies often try to impress females by dangling precariously out of their bodies in midair and lighting themselves up with reflected sun rays. Unfortunately for them, female dragonflies prefer males who hang beneath them rather than shining brightly right into their faces.

However, despite all of these reasons, none seem particularly strong enough to account for just how strongly dragonflies respond to light. And yet, somehow, these fascinating little critters manage to pull it off every single time.

In addition to having great daytime vision, dragonflies’ eyes contain lenses that focus images onto cells sensitive to polarized light. Polarized light means light waves vibrate vertically (or horizontally), instead of spinning in circles. Most organisms living today couldn’t tell between two different kinds of circularly polarized light anyway, but dragonflies can.

When dragonfly larvae grow up, their ability to recognize vertical vibration allows them not only to sense depth, but also to determine whether a nearby surface has food attached to it. If they spot a tasty grub stuck to a plant leaf, they’ll then dive toward the target to eat it. To reach deep holes in the ground, though, they must orient themselves according to horizontal polarization, meaning they’re able to distinguish between left-and-right vibrations. Dragonflies can perceive differences in polarized light through several parts of their body, including wings and antennae.

So now that we know why dragonflies sometimes get tangled up in light fixtures, let’s look next at what happens after they’ve landed.

After landing, dragonflies will usually stay put until dusk rolls around. At that point, they take flight again, searching for their preferred host species, typically mosquitoes and gnats. Once they locate a suitable meal, they land upon it, clamping their pincers around anything edible within range and consuming it quickly. Afterward, they return to wherever they were originally resting.

Dragonflies Don’t Get Tangled Up in Light Fixtures Every Time

Dragonflies Don’t Get Tangled Up in Light Fixtures Every Time

While some dragonflies do choose lights over dark areas like ponds and marshes when trying to hunt, others hardly ever go anywhere near reflected light sources. Instead, adult dragonflies tend to avoid places where they can easily become trapped in artificial structures. One way they accomplish this feat is by using reflective surfaces like mirrors to navigate. Unlike dragonflies whose eyes pick up both polarizations, mirror reflection requires light to travel horizontally across someone’s face before being redirected upward.

By sensing these changes in incoming light, dragonflies can figure out directions based on the angle at which they reflect. Interestingly, while most dragonflies can differentiate between forward and backward motion, they still show no interest in sideways motion or rotational movements. Therefore, if you want your pet dragonfly to visit your kitchen sink, you should probably keep it away from tall glass cabinets and doors that swing open or shut.

This same principle applies to the cases of dragonflies getting caught in light fixtures, too. While we know that the larger ones can occasionally end up buzzing around electric wires, they generally steer clear of overhead light strips unless they happen to catch wind of a moving vehicle passing below. Some experts believe that the biggest threat comes from electrical outlets, where the high voltage flowing through cables creates electromagnetic fields that can cause the male dragons to lose control of their bodily functions.

Female dragonflies seem less vulnerable, likely due to their longer abdomens. However, some studies suggest that the electricity emanating from household wiring poses serious risks to her eggs and offspring. Even worse, children playing with toys plugged directly into wall sockets could accidentally electrocute themselves if a stray current flows through their hands or arms and shocks them.

Are Dragonflies Dangerous?

Despite the dangers associated with keeping them indoors, dragonflies do make excellent pets. Although they require a lot of care and attention, they really shouldn’t be kept in closed containers. Their complex life cycles include four separate stages: egg, larva, pupa and imago (adult).

Adults live for approximately six weeks, and they die soon after emerging from their cocoons. Since they’re slow crawlers, they won’t hurt anyone, but unlike ladybugs and lacewings, they do bite humans. Also, keep in mind that they have piercing mouthparts that can inflict painful wounds. Lastly, remember that dragonflies are protected by international law and cannot legally be sold or given away throughout Europe, Canada, Australia and New Zealand.

Guide: Are dragonflies good for the garden?

Yes dragonflies are good for your garden, If you decide to give them a shot, here are some basic guidelines that should help keep your new friend happy and healthy. Feed them vegetables, fruits, dead crickets, earthworms, cuttlefish, daphnia, fruit flies and various types of algae. You can also buy specially formulated foods made specifically for dragonflies.

Make sure they have access to water, preferably pondwater. A container filled with sand and gravel works well. Keep them fed regularly, and check to ensure that their habitat stays clean, dry and free of debris. Provide adequate shelter from excessive rain and cold weather, as well as heat if temperatures drop below 65 degrees Fahrenheit.

Adult dragonflies can lay between 1,000 and 4,000 eggs per year, depending on conditions. Plan to provide ample space for development. Be aware, however, that once hatched, young dragonflies will consume any available food, regardless of age. As a result, they may starve to death if you forget to replace lost nourishment. Allow them plenty of room to roam freely, but don’t leave them unattended. Use appropriate insecticides against troublesome pests, and treat their enclosures with non-toxic pest repellents whenever possible.

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