You often see butterflies near the light source in your yard or outside the house on roads and parks at night.
Why Are Butterflies Attracted To Light? Butterflies are diurnal insects and are attracted to sunlight because it helps them maintain their body temperature, as they are cold-blooded. Moreover, they use sunlight as an orientation reference to navigate, warm up the muscles to get energy, take flight, find nectar-rich plants, reproduce and mate detection, and warning signals to predators. In addition, they rarely get attracted to artificial light at night if they come out in the dark.
I often see many butterflies in my flower garden at dawn when I go for a morning walk, and they give me positive vibes and happiness as they fly freely from one plant to another.
Why are butterflies attracted to sunlight?
They are attracted to the natural sunlight in the daytime because they are diurnal and forage during the day.
Cold-blooded insects
Cold-blooded insects depend on their environment to regulate their body temperature because they cannot produce their own heat.
Butterflies are cold-blooded insects and need suitable environmental conditions to maintain their body temperature.
I have built a flower garden to attract them because I love their colorful appearance and positive impression.
I often noticed theey are basking in the sun while sitting on the flower petals and feeding on the nectar.
Many butterflies gather in my garden in cold weather when the sun rises and the environmental temperature increases, which helps them regulate their body temperature.
Warm up the muscles for flight
They bask in the sun and are attracted to the sunlight because it helps them warm up their bodies and gather the energy necessary to take flights and forage the nectar-rich plants.
Once, my entomologist friend told me about their anatomy and environmental needs.
He said butterflies take energy from the sunlight, as they warm their muscles and bodies in cold weather and take long flights without problem.
He further told me about their sluggish behavior when winter comes because they become lazy and less active in these weather situations.
I was surprised when he said that some butterfly species absorb the heat from sunlight on the underside of the wings, which is also called lateral basking.
It allows them to become more active and strengthen their wings or muscles to fly from one place to another.
They cannot maneuver their flight and fly longer in cold weather, which reduces their efficiency and tendency to fly around the garden.
Orientation reference
They use the sun orientation as the navigation tool, which assists them in moving around their habitat and covering long and short distances.
They determine their location and reach their destination by monitoring the motion and position of the sun in the sky and the time of the day.
The sun orientation alone does not help much in determining the location and navigating the environment, as they use other information and sensory organs to detect their destination.
One of my neighbors knows a lot about these insects and told me about the exceptional behavior of Monarch butterflies.
They use the photoreceptors in the eyes to use the position of the sun during migration in cold weather from North America to different regions in Central Mexico.
Similarly, moths use the position of the moon and stars to determine their location and reach their habitats. Therefore, they are attracted to sunlight and moonlight at different times of the day during their active time.
Nectar-rich plants or foraging
They are attracted to it because the nectar-rich plants bloom and nourish in sunlight. The plants that provide shelter and food to these insects develop nutrients and produce nectar in sunlight.
It causes butterflies to be indirectly attracted to it because of the food sources. For example, I have purple coneflower, butterfly bush, and site lantana in my flower garden, and these plants need approximately 6-8 hours of direct sunlight to thrive.
I noticed that these plants are most likely to attract butterflies because they produce more nectar under the sun, which acts as a magnet for them to come and feed on them.
Moreover, the daytime helps them in foraging and identifying the plants that are healthy and safe for them to feed because they can detect the flowers and plants from their color and patterns.
Therefore, you often see them sitting on the flowering plants in the sun and collecting nectar to get energy and fly from one garden to another.
Natural Instinct
People relate and link butterflies with many bright and happy events due to their nature and behavior.
They are diurnal; therefore, light always acts as an attractive force for them and moves towards these areas.
The dark causes them to have less efficient vision and increases the chances of attack from predators, so they come out in the daytime and like the bright spots.
Reproduction and mate detection
They need energy and light to find mates and reproduce, which is the only purpose of their life. It allows them to detect the species fellows and the suitable mates.
They need this for successful mating, oviposition, mate detection, and finding suitable host plants to lay eggs.
My colleague in a wildlife center told me about his experience of working with an entomology department where they breed and take care of different butterfly species.
He said that the swallowtail butterflies show exceptional behavior in using the photoreceptors to ensure successful copulation and courtship displays.
It shows the importance of natural light in their reproductive strategies, as different species use this in their mating and reproduction approaches.
Warning signals to predators
It helps them show their warning colors and visual signals to deter predators. They cannot detect the predators and show them their right body colors in the dark, which causes them to move toward the lighted areas and become active in the daytime.
They can more prominently show contrasting colors and warning signals to the predators in natural and daylight compared to the species in the dark.
Therefore, the visual cues and the natural night source help them survive longer and escape the potentially threatened areas.
Are butterflies attracted to artificial light sources?
Although butterflies are diurnal, they can rarely come out at night and get attracted to the artificial light source because there is no point in going after these artificial sources in the daytime.
However, artificial illumination sources can alter many essential aspects of their habitat that appear different in natural light.
For example, I studied a research article about the effect of artificial light on butterflies, and it revealed that they do not behave the same in artificial light as in natural sources.
The reproduction strategies alter, as they cannot detect the exact color and the type of the species in the artificial or dim light at night.
Moreover, I was astounded to study that foraging activities are also influenced by artificial light, as they cannot detect healthy and safe plants as carefully as in natural light.
An experiment shows that they go after the artificial light when released at night in captivity, but the life activities are influenced greatly in different habitat conditions.
Do butterflies detect UV light sources?
Butterflies have 15 photoreceptors and can detect UV light sources without problems. They can see or detect UV patterns that are not visible to the human eye and distinguish between ultraviolet and polarized light.
They have an ultraviolet reflective pattern on their bodies, which serves as the courtship display and helps them detect or repel other males from their female mating fellows.
Moreover, they can detect the UV reflections on the flowers, as some flower petals can absorb or reflect the UV rays, which helps them spot the food source.
They use the photoreceptors in the eyes on their head to detect the UV light reflections and sources around their habitat.
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