Monday, March 10, 2014
By Tom Atwell
With honeybees becoming scarcer and more expensive to bring in from out of state, wild and native bees are becoming more important to commercial growers and home gardeners.
Maine blueberry growers bring in about 75,000 hives of honeybees to pollinate their crop each year. While that is way behind the 900,000 hives that California almond growers bring in, it still is expensive – especially since the cost has jumped from about $35 per hive about a decade ago to $150 per hive now.
It would be a lot more efficient to depend on the approximately 260 species of native bees that live in Maine – if they have enough food to eat to keep them around when the blueberries are not in bloom.
The University of Maine is conducting a study at gardens at Old Town, Jonesboro and Blue Hill to determine what flowers are most attractive to bees. The experiment is being conducted by Alison Dibble, Lois Berg Stack and Frank Drummond, all professors at UMaine, assisted by Eric Venturini, a graduate student. Dibble discussed preliminary results at the Maine Landscaping and Nursery Association trade show while Venturini discussed them at a Maine Organic Farmers and Gardeners meeting at the state Agriculture Show, both held last month in Augusta.
Dibble said the experiment involves planting one square meter of several flowering plants, and having researchers count how many bees, and what species of bees, come to each plot during three one-minute periods.
The flowers selected to attract bees, if you are growing blueberries, should not bloom at the same time as blueberries, Venturini said. “You want them to use the blueberries.”
That is especially true if you are using honeybees.
“Honeybees really do not like blueberries,” Dibble said. “If there is anything else, they will go to that.”
And since bees are active for about seven months, from early April until early November, they need flowers throughout that period to thrive. While honeybees are said to travel several miles to gather pollen and nectar, Dibble said, small bees have a practical range of 200 to 300 feet.
Maine’s 260 bee species include bumblebees, miner bees, sweat bees and more, and most of them are solitary bees, do not sting people and do not create honey – even though they are great at pollination. Different types of bees are attracted to different flowers. As an example, Venturini said, most solitary bees are attracted to coreopsis, but bumblebees are not.
In the early season, bees get a lot of their food from maple trees, but the bees also like willows – native pussy willows and the Japanese versions – before the blueberries are in blossom. She also mentioned serviceberry and coltsfoot – which looks like a dandelion – as early-season pollen plants.
A lot of plants blossom in June, including blackberries, clover and dandelions, as well as a lot of ornamental garden plants. Dibble praised Greek oregano as being highly popular, especially with bumblebees and sweat bees. It blooms from June through August and it is highly edible.
Elderberry flowers provide a source of food for native bees, and the bees also like the hollow stems of elderberry plants as nest sites. She said gardeners can help by providing good habitat for the bees, including hollow stems and bare, dry ground for miner bees.
Dibble said that while butterfly milkweed, asclepias tuberosa, is a required food for Monarch butterflies, it also provides food for bees in August and September.
Other mid-season plants include borage, anise hyssop, thyme, purple coneflower and borage.
Late-blooming plants are especially important, because there are not that many flowers blooming at that time. One good native is asters, which attract honeybees, bumblebees and sweat bees. Asters come in a variety of colors and are easy to grow.
Dibble also praised goldenrod, although many people consider it a weed. It is native, and the Europeans are doing more with goldenrod hybrids than the Americans are.
Clethra, a hardy native shrub, attracts many different bees late in the growing season.
She said bottle gentian is one of the last plants to flower, and attracts a lot of bees.
The UMaine study is in the second of five years, so the results reported now are just preliminary. I’ll keep following it.
On a related topic, Erin Forbes, past president of the Maine State Beekeepers Association, called to tell me that a bill I wrote about in December to put a moratorium on the use of neonicotinoids in Maine is being withdrawn.
Forbes said the bill as drafted has problems, and the association and Rep. Brian Jones, its sponsor, agreed to drop this bill and work together on a better proposal, which they plan to introduce next January.
Tom Atwell has been writing the Maine Gardener column since 2004. He is a freelance writer gardening in Cape Elizabeth and can be contacted at (207) 767-2297 or at: