WHAT DO BEES SEE?
The way insects see the colorful world of flowers differs from our perception. Human vision is based on the colors red, green, and blue. Insects, however, can also see in the ultraviolet (UV) part of the spectrum. Plants make use of this phenomenon by advertising secret messages to those who can see in UV. These can be messages of how to spot the nectar, where the pollen is, or landing strips on the flower. And so, during millions of years, a mutual beneficial relationship evolved: ingredients for honey in exchange for pollination.
ONE HUMAN LENS vs. MANY INSECT LENSES
Just like an old-school camera, the human eye is made up of one lens with a surface to capture the image. When we look at an object the lens focuses on the light that comes from the object onto the back of our eye and then onto the retina. Light sensitive receptors on the retina send an electrical signal to the brain. Our brain receives these signals plus the signals that have come from our other eye. It combines them, and we “see” the object.
Insects, including bees, have a different set-up. They have compound eyes, which are made up of thousands of tiny individual lenses. The eye of a honeybee worker has almost 6,000 lenses. Based on the principles of the human eye, we might think that the honeybee would see 6,000 images of an object. But, just as in the human brain, the bee brain combines all these signals. It produces a composite image from these 6,000 snapshots. A bit like a digital camera and its pixels, the more lenses the more detailed the image. The honeybee queen flies just a few times in her life, so she doesn’t need to see very well and has only 3,500 lenses. A male honeybee, who must chase a queen to mate with her on the wing, has 10,000 lenses per eye – all the better to see her with!
WE SEE RED, while BEES SEE PURPLE
Humans and bees are trichromatic – our perception of color is based on a combination of three colors. In humans these colors are red, blue and green. The human eye has receptors for all three but there is a part of the eye that is particularly rich in red receptors. It has green receptors too, but no blue receptors at all– this is called the Fovea. The image that comes through our eyes falls on this spot, and our vision is sharpest here. Red/green is the color of ripe fruit amongst green leaves. Red is for lipstick and warning signs – we are alert to it.
A bee’s color receptors are ultraviolet, blue and green. They can see reddish wavelengths such as yellow/orange, but because bees don’t have a red receptor, they can’t “see” red light. The color we see so vividly is, quite literally, unseen by bees. Bees see blue-green, blue, violet and “bee purple”. Bee purple is a combination of yellow and ultraviolet.
This is where bees’ inter-relationship with flowers comes in. Flowers rarely reflect one color of light, and many reflect ultraviolet light. Flowers that may seem very similar to us are easily distinguished by bees based on color: for example, canola blooms and field mustard. Petals can also have visual aspect that is clearly seen by bees, but which may be hard for humans to see at all. Nectar guides, which point the insect to the center of the flower, are an example of these often “hidden” patterns. The bee gets the reward of nectar that it lands on – and the flower gets pollinated.
The most likely flower colors to attract bees are purple, violet and blue. The red flowers that are so striking to humans are probably just “black” to bees, unless the flower reflects some ultraviolet. We can’t know what bees really see, but their inability to see red is useful to consider if we want to plant for these pollinators.
PATTERNS IN THE SKY
Bees have a type of light perception we lack completely: bees can see polarized light.
Light from the sun vibrates in all directions. Passing through the earth’s atmosphere makes it vibrate in one direction – it has become polarized. As a result, the sky has a visual pattern. The pattern begins at the sun and extends out across the sky. Unlike humans, bees can see this pattern. Because the pattern originates from the sun, it has direction. The bees can navigate using it, even on cloudy days. The worker bees out in the fields collecting nectar use this perception along with their instinctive sense of time to find their way home to their colony.
Click the link to watch an amazing YouTube video which shows the same flowers though the eyes of humans and bees. It also shows the butterfly’s eye view, another important group of pollinators that see the world very differently from us. Dr. Klaus Schmitt from Weinheim, Germany, made these stunning UV pictures, simulating the perception of colors by insects. This film is made by media artist Robin Noorda for the ‘Photosynthesis’ exhibition of the art movement Tropism.
YouTube https://www.youtube.
It is impossible for us to experience the world the way a bee does, but it’s fascinating to imagine the pixelated, purple and patterned world they inhabit.
To create a bee-friendly garden in Colorado, plant a variety of blue, purple, yellow, and white native flowers that bloom from spring through fall. Drought-tolerant and UV-reflective plants that attract Colorado’s 900+ native bee species include Rocky Mountain Penstemon, Bee Balm, Lavender, Sunflower, and Blanket Flower. For best results, look for locally sourced seeds.
Best Plants for Colorado Bee Gardens
- Perennials: Rocky Mountain Penstemon, Native Bee Balm (Monarda), Blanket Flower (Gaillardia), Yarrow, Goldenrod, Aster, and Sedum.
- Herbs: Lavender, Hyssop (Agastache), Thyme, Mint, and Sage (Salvia).
- Shrubs & Fruits: Raspberry, Blackberry, Serviceberry, and Cherry trees.
- Spring/Early Season: Crocus, Wallflower, and Chives.
Tips for Success in Colorado
- Plant in Groups: Group the same plant species together to make them easier for bees to find, rather than scattering them.
- Choose Native: Native plants like Rocky Mountain Bee Plant and Showy Milkweed are adapted to local climate conditions.
- Continuous Bloom: Select plants that bloom at different times (early, mid, late season) to ensure a steady food source for the entire season.
- Water Wise: Many bee-friendly plants thrive in Colorado’s dry, full-sun environment with minimal water, such as Russian Sage and Sedum.
- Avoid Pesticides: Minimize or eliminate the use of pesticides, which can harm or kill native bee populations.
CSBA also offers a “Plant Forage” article with informative and helpful links. https://