Are Bees Attracted to Light?
Bees play a critical ecological role as pollinators for flowering plants, including many agricultural crops. There are over 20,000 identified species of bees globally, each equipped with specialized adaptations to seek out flowers and transport pollen. An interesting behavioral question is whether bees, like some other insects, demonstrate attraction to light sources. Understanding bee responses to light could have implications for strategies to control them or modify their activity in anthropogenic settings.
This article explores the light orientation tendencies of bees, covering topics such as:
- The types of light that attract bees
- Why bees evolved navigation toward light
- Experiments demonstrating bees moving toward light sources
- Differences in light attraction between bee species
- Applications of bee light attraction behaviors
- Risks artificial lighting can pose to bees
- Methods to reduce light pollution impacts on bees
Gaining insight into bee interactions with light not only sheds light on their sensory world, but may assist efforts to reduce detrimental disturbances to essential bee populations already under stress from other factors.
Types of Light That Attract Bees
Bees visually navigate using inputs from their well-developed eyes, which include three ocelli and two large compound eyes. These sophisticated eyes respond to a range of light cues:
- Sunlight – Bees instinctively orient towards direct sunlight as it indicates the location of flowering plants. They track the sun’s movement across the sky through optical sensing and circadian rhythms.
- Polarized light – Specialized photoreceptors detect polarized patterns in scattered skylight, informing navigation.
- Ultraviolet light – Many flowers have UV-reflecting patterns guiding bees to nectar. Bees see UV wavelengths invisible to humans.
- Bright white light – Intense artificial light often mimics daylight, tapping into bees’ attraction to floral light environments.
While bees do not see the full color spectrum humans do, they adeptly distinguish light intensities, polarization, and UV signals that guide their foraging flights.
Why Bees Evolved Attraction to Light
Positive navigation toward light evolved in bees as it led predecessors to optimal flowering locations with greater efficiency, improving feeding and reproduction. Drawn to light, bees located essential resources. Key advantages include:
- Sunlight indicates exposed flowers and warmer conditions preferred by cold-blooded bees.
- Skylight patterns helped orient bees in appropriate directions during foraging.
- UV reflections off plants allowed bees to better pinpoint nectar-bearing parts.
- Light informed circadian rhythms regulating activity levels aligned with floral availability.
- Light guided bees towards potential nesting cavities.
Through natural selection, bees that responded positively to light signals flourished compared to those indifferent or repelled by light cues in their environment. Today, this attraction persists, usually benefitting bees but also making them vulnerable to unnatural lighting.
Experimental Evidence for Bee Attraction to Light
Controlled laboratory experiments confirm bees exhibit movement toward light sources rather than randomness or aversion:
- Bees strongly prefer illuminated feeders and will abandon shaded ones.
- When presented with multiple options, bees choose more brightly lit flowers over dimmer samples.
- Bees conditioned to associate a certain color light with nectar will fly preferentially toward that color.
- When the sun position shifts, bees will follow and repeatedly reorient dance patterns to track the moving light.
- Disrupting the ocelli impairs light-guided orientation, indicating their role in sensing direction.
- At night, bees become confused navigators but still fly toward artificial lights, unable to find the hive.
The phototactic behavior measured empirically demonstrates bees instinctively move toward light in many situations.
Differences in Light Attraction Among Bee Species
While most bees exhibit attraction to light, some variations occur based on niche adaptations:
- Honey bees rely heavily on daylight cues for hive navigation. Their complex communicative “waggle dances” incorporate skylight patterns.
- Orchid bees foraging in shaded forest settings focus more on olfactory cues than visual light signals.
- Mason bees choose naturally dark nesting cavities and may avoid overly bright areas.
- Nocturnal bees like Megalopta avoid light and are active in dim conditions. They locate flowers by scent and touch.
- Hiveless male orchid bees form nightly resting congregations, possibly using dim light for orientation.
- Sweat bees follow sun flecks penetrating forest canopies to find transient floral resources.
Different species balance light orientation against other sensory information like smell based on ecological roles. But most demonstrate attraction rather than repulsion.
Applications of Bee Light Attraction
The draw bees feel toward light and sunlight provides opportunities for manipulating their behavior:
- Large field arrays of polarized light panels can steer bees away from airport runways and other perilous locations.
- Traps often use bright colors and transparency to be more visible to attract bees in for population control.
- Covering beehives and entrances with dark screens calms bees by blocking light.
-strategically planted flowers that reflect UV light can help draw bees toward crop fields and orchards needing pollination.
- Translucent beehives allow light to pass through, reducing erratic fly outs.
- UV-absorbing films placed over greenhouse glass admit sunlight while deterring bees from entering.
Better understanding bee orientation to light facilitates approaches for safely steering them out of harm’s way and into locations where they can assist with pollination.
Risks Artificial Lighting Poses to Bees
While bees innately move toward light, anthropogenic lighting presents challenges:
- Disorients navigation and foraging, leading bees astray from hives and flower resources.
- Interrupts natural circadian rhythms oriented around sunlight patterns.
- Can induce bees to remain active through the night, leaving them exhausted and more vulnerable.
- Light pollution near hives may impair hive mate communication and synchronization.
- Attracts bees toward perilous locations like busy roadways.
- Causes bees to cluster on intensely lit surfaces, risking injury or death.
Artificial light attraction goes awry in human settings, directing bees into confusion, exhaustion, and mortality rather than sustenance and home.
Reducing Artificial Lighting Impacts on Bees
Some ways to mitigate detrimental bee attraction to human-generated light include:
- Shielding light fixtures such as streetlamps to concentrate illumination below rather than horizontally.
- Choosing amber or red tinted LED lights which attract bees less than white/blue light.
- Dimming lights to the minimum level needed during overnight hours when bees become most disoriented.
- Avoiding placing lights directly around or near the entrance to beehives, which interferes with their cues.
- Educating homeowners to only use necessary exterior lighting and shield fixtures.
- Planting hedges and refuge areas away from lights to help draw confused bees back to safety.
- Mounting ultraviolet light filters on greenhouses to permit healthy growing light while keeping bees focused outside.
With conscientious lighting practices, human activity can better coexist with the needs of essential pollinating bees that rely on natural light patterns.
Bees have evolved strong instinctive attraction to light, which guides their foraging and navigation. But human introduction of artificial lighting at night often disrupts these hard-wired behaviors, leading bees astray. Though originally adaptive in the natural world, light orientation makes bees vulnerable in human-altered environments. Thoughtful mitigation of light pollution, along with efforts to preserve bee habitat and food sources, can foster a safer, healthier coexistence. With care, our own needs can still be met while respecting the light-seeking nature of bees.