Seven years ago, it was an incidental finding. I was preparing to lead a tree walk at Linden Grove Cemetery and Arboretum and was canvassing the grounds, assessing the tree inventory for interesting specimens. As I did so, I came upon a large tree that was hosting a bee hive – quite a surprise. The opening to the tree cavity was a swarm of activity as a mound of bees hustled to get in. To put the element of surprise in perspective, I was in an urban cemetery, approximately a mile from downtown Cincinnati, as a Honey Bee flies – not a likely location for a thriving hive.
Each of the past six years since, I have revisited the tree and have seen no bee activity. Then one day last week I had a full schedule, trying to run some errands before joining a friend to carpool for an afternoon of golf. With my errands completed before our meeting time, I decided to forego scrolling social media in the parking lot, and instead chose a quick visit to the historic Linden Grove Cemetery – and was rewarded when I found my bee tree repopulated with a Honey Bee colony.
It was a somewhat cool day and the bee numbers were not dramatic, but undeniable. I texted the photographer to share the excitement. While man-made bee hives are interesting to me from both an ecological and horticultural perspective, to see bees colonize a tree cavity is a whole new level of engagement.
Two days later, on a brighter and warmer day, we returned for further study. The host tree is massive,
but the opening into the trunk is less than obvious. It is twenty-two feet off the ground and on the north side of the tree, making photography a challenge, due to the sun in the south.
Perhaps due to the warmer temperatures and sunshine, the bee activity was significantly greater on my second visit. I think that this video demonstrates it best. Keep in mind that this opening in the tree is 22 feet off the ground.
The experience left me with several questions – what caused the earlier colony to leave? Why the six year absence?
Honey Bee colonies disappear for two reasons: Due to health or due to unsuitability of the site. So perhaps the earlier brood was infested with the bee mite that led to a decline in the number of bees and eventual collapse of the colony. They may have also been driven out by ants. Another potential issue was the north facing opening, which is not ideal to bees. They prefer an east or southeast facing opening which is more protected from the weather and receives morning sun to warm up the colony. The warmth allows for earlier foraging. Finally, the large colony may have found that there were not enough nectar and pollen sources in this urban setting to support them. As a result of any or all of these reasons, they may have moved on to a more desirable location.
The fact of the matter is that that I have entirely romanticized the allure of the “Bee Tree”. After all, Honey Bee trees in the U.S. are an outlier and not a normal circumstance of our ecosystems. I failed to keep in mind that the Honey Bee is a non-native, brought to North America by the colonists in the 1600s. They are native to Europe, Africa, and western Asia. In those areas they develop colonies in tree cavities, but that is not typical in the U.S. In the States, those in tree cavities are vagabonds, escapees from those historically housed in structured bee hives at apiaries. In the bee keeping community they are referred to as “feral” colonies.
If Honey Bees are not native to the U.S. why is their survival considered so important to our agricultural industry? Because most of our agricultural plants are not native to the U.S. and happen to originate in the same regions of the world that the Honey Bee is native to – apples, citrus, cherries, lettuce, kale, cabbage, and melons, for example. It turns out that when it comes to pollination, the many species of bees are specialists and frequently only interact with a select group of plants. Honey Bees happen to be very good at pollinating our agricultural plants that also originated in the same regions of the world that the Honey Bees are native to.
Likewise, the Dandelion is native to Europe, and is a favorite food source for honey bees in Linden Grove and elsewhere.
Whether the Honey Bee colony is in a tree cavity or a man-made hive, the culture of the colony is the same – it is female dominated. The colony is ruled by the queen bee who can live for 3 to 5 years. There can up to 80,000 bees in a colony, with the more typical range being 20,000 to 60,000. Ninety-nine percent of the bees in a colony are female and they play many roles. When they are young they are nurse bees, tending to the larvae and the queen herself. They also convert nectar into honey and package it for storage. As they get several weeks old they become worker bees, leaving the hive, traveling up to 1.3 miles. Some will function as scouts, traversing the landscape looking for sources of nectar, pollen, and water, and then communicate the locations to the remaining worker bees who will collect these items and bring them back to the hive.
Nectar is turned into honey which is the primary food source for adults and larvae. Pollen is fed to larvae as a source of protein. The orange structures on the legs of the bee in the photo below are pollen baskets, bringing collected pollen back to the nest.
Water is brought back to the hive for drinking, but its evaporation is used for cooling the hive as well. The video below shows a large number of bees landing on lily pads to collect water to take back to a nearby hive.
The average lifespan for a female worker bee is only 51 days. They succumb to predators, insecticides, and getting lost. The queens lay on average 1500 eggs per day to replace those that have been lost.
The only job of the male bees, which have no stingers and are referred to as drones, is to find a a new queen who is in search of a mate, to pass on the genes of the colony.
Two things will trigger the development of a new queen. First, as the queen in a colony ages, there will be a drop in her levels of a hormone called pheromone. When that drop is perceived by the worker bees, they will build a specialized nursery for the development of a new queen. Ten to fifteen cavities are developed and the queen will fill each with an egg. These larvae are fed a specialized diet that leads these females to develop reproductive organs. Eventually one of the larvae will pupate and then emerge. She will immediately kill off the remaining larvae and pupae that were destined to become queens, and then soon after leave the colony on a mating flight and mate with multiple males, up to 10 to 20, that she encounters. This is the only time in her life that she will mate, but she will lay fertile eggs for several years. The multiple mates allow for genetic variation in the colony and improves overall colony health. The newly mated queen usually returns to the nest, kills the old queen, and takes over the colony. The other scenario that leads to the development of a new queen is if the colony is thriving and outgrowing the hive. The old queen will take approximately half of the worker bees and establish a new colony. The remaining nursery worker bees will feed the specialized diet to some larvae that leads to the development of a new queen. When the old queen leaves the nest with half the workers, this is termed a swarm. The relocating colony will temporarily position themselves somewhere while a small number of bees, the scouts, will travel the landscape looking for a suitable cavity to nest in. These swarms, when noted in residential communities, can cause an element of alarm but are of no threat. A swarm is probably how the Bee Tree at Linden Grove got repopulated.
During the winter the bees do not hibernate as such but they settle themselves into the hive and cluster together, living off stored honey. They will activate their flight muscles to generate heat. The bees that overwinter will live for approximately six months.
So to close this story I will tell you that the hive is in a massive Blue Ash tree, a somewhat rare tree in Northern Kentucky. It can be identified as an ash by its opposite branching, and as a Blue Ash by the square nature of the end twigs, as seen in the photo below.
In addition, Blue Ashes have a unique bark among the ashes, one that is more plaque-like and less ridge based. In the photos below the Blue Ash is on the left and a White or Green Ash is on the right (White and Green Ash can not be identified specifically until they leaf out).
Lastly, a photo taken at the base of the tree to document the proximity of the bee tree to downtown Cincinnati.
On a sad note, I’m afraid that this tree’s lifespan is limited, for as we looked on its south side we found this exposed heartwood which is being destroyed by insects and fungi. It appears to be an incompletely healed lightning injury. Decaying heartwood will lessen its structural integrity and make the tree more susceptible to storm damage.
In summary, stumbling on to the Bee Tree became a fun academic exercise. I had to rethink my entire embrace of the Bee Tree being a holistic example of a healthy ecosystem, since Honey Bees are not native to North America. It also forced me to reason through why they are so integral to the success of our agricultural industry – because many of our agricultural plants are also non-native, and rely on their evolutionary relationship with the Honey Bee for successful pollination. With that said, I must confess that I am a big honey fan, especially when applying it to a hot, buttered biscuit, or when I am under the weather and mixing it with bourbon and lemon juice, to make our “For Medicinal Purposes Only” hot toddy – see the link to the recipe below.
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Photo and video credits to Peggy Juengling Burns with the exception of the bees collecting water video which was by Patrick Burns.
Overview:
Location – 401 West 13th Street, Covington, KY, 41011
Parking – Asphalt lot for 20 cars.
Facilities – none
Trail Conditions – this is an amble along a flat, gravel road.
Benches – several spread across the cemetery campus.
Picnic Tables – one noted
Print Map Link – none. Everything is within sight.
Kids – a stroller with big wheels would do well on the gravel path.
Dogs – welcomed.
Suggested Paired Hikes – none
Links:
https://historiclindengrove.org/
https://burnsfamilyrecipes.wordpress.com/2016/02/14/for-medicinal-purposes-only/