The sound of buzzing insects is so loud that it stops you in your tracks during a walk in the woods. Looking around, you find a tree laden with large, 10-12” clusters of small creamy white flowers with every bee, wasp, and fly in the neighborhood buzzing around. Then you notice that there are more trees and more bees, wasps, and flies. The noise is deafening. What is this tree that is so popular with pollinators?
This is the bee-bee tree, Tetradium daniellii, also known as Korean evodia. It grows to 30’ tall with a similar spread and has smooth, dark gray bark with small white lenticels. The compound leaves are opposite with smooth, shiny, dark green leaflets. The tree can be mistaken for young native ash trees (Fraxinus sp.) or tree of heaven (Ailanthus altissima) in all sizes. Ash trees also have opposite leaves; tree of heaven has alternate leaves.
Bee-bee trees are either male or female; that is, the male or female flowers are on separate trees. Both produce large, clustered flower heads. The female flower heads turn a wonderful red as the seeds ripen for a second decorative show. The seeds resemble dark black BB pellets and each female tree produces thousands of seeds. This leads to thick dark stands of bee-bee trees under which few other plants will grow. Even Japanese stiltgrass (Microstegium vimineum) does not grow underneath. The seedling crop is so dense that you can’t move without stepping on seedlings.
Beekeepers love this tree because it blooms in the hot dry part of the summer. As a landowner and beekeeper, I do not like this tree. The tree was planted in arboretums in the mid-Atlantic many years ago and now it is found invading the surrounding areas from its original planting sites. It has invaded several acres on our property and is outcompeting the tree of heaven in that area. This is a feat; it worries me that we will lose even more of our woodlands to these invasive trees.
Bee-bee tree has invaded Michaux State Forest outside of Mont Alto, PA, where it was planted at the Penn State Mont Alto campus, probably the source of our infestation just south of Mont Alto in Maryland. It has also spread around Morris Arboretum, the Virginia State Arboretum at Blandy, VA, and throughout the U.S. National Arboretum in Washington, DC.
Our property is one of three sites being studied by a Towson University graduate student to define the tree’s impact and methods of invasion in our region. We have found the only effective method to treat the invasion is by cutting down the trees and treating the stumps with glyphosate. It will take us years to insure the tree is no longer found on our property. It may be a magnet for bees, however it is suppressing and outcompeting the native plants that our native bees and insects need to survive. We hope others will join us to catch it before it takes over.
Additional Resources
- Should the Bee-Bee Tree be Avoided? | Maryland Invasive Species Council
- Invasive Plants in Pennsylvania: Bee-Bee Tree | Pennsylvania Department of Conservation and Natural Resources
- Introduction to Invasive Plants | University of Maryland Extension Home & Garden Information Center
By Ann Aldrich, beekeeper, native plant expert, small farm owner in Washington County, Maryland