Plants Toxic to Bees
It may sound crazy, but some of the flowers you choose for your landscape may be dangerous to bees. In fact, some plants are toxic to bees. As bees gather nectar and pollen from flowers, they choose the best available source. In times when food sources are sparse, they may turn to flowers that cause harm. Is this a big problem? In most cases no, lets look at the details.
While choosing plants and flowers for bees, you want some that are visually appealing to you as well. Unfortunately, beauty to the human eye may not be a beautiful idea for bees.
Why Are Some Plants Toxic to Bees?
For the most part, plants and pollinating insects have a symbiotic relationship. Flowers provide nectar and/or pollen. In return, bee pollination results in more fruit and seeds for the plants.
However, the sap, nectar and pollen of some plants contains chemicals toxic to bees. We do not know for sure why this happens. But perhaps, it is the plants way of only attracting special pollinators.
List of Plants Poisonous to Bees
The following flowering plants may be poisonous to honey bees – at least under certain conditions. The important word here is “under certain conditions“.
When weather conditions are fine, some of these plants can actually help bees. There is no need to eradicate all from the landscape. However, it might be a good idea to avoid them when choosing new plants for the garden.
- American Basswood (Basswood tilla) – only in times of drought – otherwise excellent source
- California Buckeye (Aesculus californica) – biggest threat during drought
- Jimsonweed (Datura Stramonium)
- Mountain Laurel (Kalmia latifolia)
- Rhododendron (Rhododendron spp.)-some species
- Summer Titi (Cyrilla racemiflora)-causes purple brood disease
- Yellow Jessamine (Gelsemium sempervirens) -Carolina Jessamine
Toxic Plant Nectar
While pollen from certain plants can be poisonous to bees, the largest culprit is nectar. Honey bees collect nectar in large quantities.
When this nectar is transformed into honey, it may be toxic to the bees or even humans in some cases. Should you be very worried about consuming toxic honey from your bees?
For the most part, the answer is no. It is rare for honey bees to collect enough poisonous nectar to harm themselves or you.
When many of these plants are blooming, other nectar sources are more attractive. Chances are the bees will not zone in on the toxic plant.
Nectar Dilution Affects Toxicity
As with many living things, the degree of toxicity for poisonous nectar is often related to dosage. During a normal season with good foraging conditions, bees choose other nectar sources.
In the case that some of the foraging bees do visit poison plants, the nectar will be diluted back in the hive. As it is mixed with nectar from thousands of other flowers, it becomes less harmful to the colony.
This is a great reason to include some drought tolerant bee friendly plants in your landscape. Give the bees a choice.
Azaleas, Rhododendron, Mountain Laurel & Bees
Rhododendron and Mountain Laurel grace the hillsides of my region near the mountains of South Carolina. Only once in many years of beekeeping – have I seen bees working those blossoms.
However, you will hear of years where a very late freeze killed many of the early Spring blooms. Then the bees turn to any available food source.
Beekeepers in areas just north of here did experience some “Mountain Laurel Honey”. The bees were fine for the most part and the beekeepers as well-to the best of my knowledge.
There is no need to run outside and rip your Rhododendron and Azaleas from the landscape. In most cases, your bees will ignore the toxic plants. They will choose instead to forage on better nectar sources.
When there have been reports throughout history of humans being sickened by consuming toxic honey from this nectar, this is a very rare occurrence.
Beekeeper Tips
Most beekeepers will never experience a problem with plants killing their bees. My water gardens provide a water source for my bees.
The Pitcher Plants, Sundews and Venus Fly Traps are designed to attract and trap insects. Yet, it is rare for me to find a dead honey bee inside any of them. Plenty of ants and gnats but very few bees.
Beekeepers should monitor bee activity during nectar dearths, droughts, late freezes, etc. For beekeepers with large apiaries, learn which plants are in your area that could be a problem.
If needed, consider feeding sugar water to the bees during times of need. Even short term feeding can be beneficial in these cases.
FAQs
In most cases, plant nectar that is toxic to bees does not result in honey that is poisonous to humans.
Toxic nectar and pollen rarely kills a whole colony of bees but it can cause problems in the hive: loss of foragers, loss of young brood, etc.
Yes, bees use plant nectar to make honey from any blooming plant. The resulting honey may or may not be harmful to humans.
Yes, bees can pollinate the blooming flowers of poisonous plants.
A Final Word
In most cases, it is highly unlikely that your bees will suffer from toxic plant nectar or pollen. However, it is the wise beekeeper who understands foraging conditions and is observant of environmental factors that can change each year. And gardeners seeking to provide resources for insects and other pollinators – may want to consider all the options available.