- Author: Kirsten Pearsons
Everyone can appreciate the beauty of flowers, but that's not to say flowers look nice just for us! We often get asked by Haven visitors how bees find their flower hosts. One way is through unique flower colors and shapes. Once bees are near a plant, flowers with intricate patterns can entice them even further through patterns on the petals that direct bees straight towards nectar rewards. Like runway lights at the airport, these intricate nectar guides can help orient pollinators during their flower visits.
Nectar guides are doubly useful for bees, as they use guides at individual flowers to find nectar faster and as search images to target similar flowers. Since plants of the same species tend to be flowering at the same time, loyal bees can be more efficient than bees that hop from one species to another. It's a win-win situation since loyal bees can collect nectar with less effort and the flowers get a greater chance of receiving pollen from their own species (Functional Ecology 2011, 24, 1293-1301).
So what about simple monotone flowers? Well, the thing about nectar guides is that we humans can't always see what the bees do! We can see all of the colors from red to violet, but bees see a shifted spectrum from yellow through ultra-violet (UV). So to bees, even seemingly plain flowers may have bold nectar guide patterns. With UV sensors, even humans can get a glimpse of what nectar guides look like to bees. (Plant Species Biology 2013, 28, 177-184). The web site Flowers in Ultra-Violet has many images comparing flowers in daylight and UV light in which the guides are visible.
Other than bees, hummingbirds, hawkmoths, and syrphid flies have been found to respond to nectar guides. Some flowers even have overlapping visible nectar guides and UV nectar guides, possibly to attract birds and bees simultaneously. (Functional Ecology 2011, 24, 1293-1301).
As you walk through the Haven, look at our flowers for these intricate patterns. Here are two of the species in our garden with visible nectar guides:
/div>- Author: Christine Casey
Bees need flowers that correspond to their body size and tongue length in order to effectively access the nectary located at the flower base, so a well-designed bee garden includes plants that provide a variety of flower shapes and sizes. Small bees with short tongues, for example, need a small, open flower like yarrow to feed effectively.
To further complicate matters, some bees have learned that they can access otherwise unavailable flower resources by nectar robbing. These bees have learned to chew a hole at the base of flowers; through this they insert their tongue into the flower to access a nectar reward they would otherwise be unable to reach. Since the insect never enters the flower there is no pollination, and ecologists are now beginning to study this behavior to determine if it impacts flower populations in the wild.
But that's not the end of the story. Clever honey bees will observe the larger bees creating holes and will use them as well. Nectar robbing is often seen on tubular flowers, and in the Haven we see it most frequently with carpenter bees and bumble bees on penstemon and salvia.
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