Solitary bees could be more efficient than honey bees, researchers say
By Sarah Cato
U of A System Division of Agriculture
June 7, 2018
Fast facts:
- Solitary bees make up most of the world’s bee population
- Could be more efficient pollinators than honey bees
- Can easily be encouraged in home gardens
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LITTLE ROCK – Consider yourself warned, honey bees: the solitary bee may steal your spotlight.
Although honey bees often dominate the discussion when it comes to the world of winged pollinators, Jon Zawislak, apiculture instructor for the University of Arkansas System Division of Agriculture, said they’re actually outnumbered by solitary bees.
“Most of the world’s estimated 20,000 species of bees are solitary bees,” Zawislak said.
As the name implies, he said, solitary bees are not very social — unlike honey bees or bumble bees.
“Very few bee species live together in colonies,” Zawislak said.
Each female solitary bee establishes her own nest after mating, and creates a series of small brood cells. Male bees die immediately after mating. Their lack of sociability, he said, could be what makes solitary bees so efficient.
“Once a female has started a nest, she begins gathering the pollen and nectar to provision it,” Zawislak said. “Because these solitary bees are not trying to store an enormous amount of honey to feed thousands of colony members all winter, they spend much more time gathering pollen to supply their own brood. For this reason, these bees are considered to be very efficient at pollinating flowers.”
But this isn’t the only reason these bees can be more efficient than honey bees.
“Also, honey bees can forage up to several miles from home, while many solitary bees will likely never go more than a few hundred yards from their nests their whole lives,” he said. “This makes them ideal pollinators for small scale backyard gardens.”
Zawislak said that, while plant preference will vary from bee to bee, some plants are much better off with some native pollinators.
“Native plants attract native bees,” he said. “Some bees are highly specific about the plants they will pollinate while others are more general. But for new world plants like pumpkins, squash and blueberries, native species are more efficient at pollination than honey bees, which were originally imported from Europe.”
Building a house
Nesting blocks for solitary bees and other native species are not hard to make and can attract some pollinating guests to your garden.
“Simple nesting blocks can be easily produced by drilling holes in any piece of untreated wood,” Zawislak said. “Different species prefer hole diameters ranging from one-eighth to three-eighths of an inch. Homeowners can experiment with various sized holes in increments of one-sixteenth of an in or less and see which sizes appear to attract the most bees in the area.”
Some other measurements that should be taken into consideration are depth and spacing.
“Holes should be spaced at least three-fourths of an inch apart and be three to six inches deep, and they should not be drilled all the way through,” Zawislak said. “This is important because bees will not nest in a tunnel that is open at both ends, and many store-bought native bee nests unfortunately may not be constructed properly.”
If you don’t have a drill, there are other ways to make a nest.
“Sections of hollow cane or bamboo can also be bundled together to provide solitary bee habitats,” Zawislak said. “Just be sure to cut the bamboo just behind a node, so that the tunnel has a solid back wall on one end.”
Once the bees get settled in, they start to make the house a home.
“Bees will divide the tunnel into numerous cells,” Zawislak said, “then bees deposit female eggs toward the rear of the tunnel, while male eggs are usually place in the front, towards the entrance. In case of predation, only males will be affected.”
Depth of the hole should be decided carefully, as different depths have different results.
“Deeper holes will accommodate more female bees, and therefore increase the number of pollinators for the next season,” Zawislak said, “but holes that are too deep may not be utilized.”
There is a trick to moving and cleaning, but watch out for some unexpected, yet helpful, guests.
“Some people use paper tubes or straws to line nesting blocks so that they can be removed and the blocks can be cleaned properly,” Zawislak said. “Occasionally solitary wasps will take up residence in these holes, but these rarely become a problem, and may also contribute to biological control of caterpillars and other pests.”
These bees like to stay close to home, and when fall rolls around they leave behind quite a surprise.
“These nesting blocks can be placed around the landscape to attract bees and promote pollination, because the bees that establish in those nesting holes will forage and pollinate in the immediate vicinity around the nest,” Zawislak said. “In the fall, when no more bee activity is observed, the tunnels should appear plugged with mud or leaf bits, which mean it’s full of overwintering bee pupae!”
Placement of the nest is important and can change depending on time of year.
“These nests can be gently moved to a new such as an orchard or garden before the spring emergence to encourage local pollination,” Zawislak said. “They can be sheltered in a shed for the winter, but they should not be placed in a heated environment or they will overcome their dormancy too soon.”
Zawislak said protection from rain should be considered when placing the nest.
“Nesting blocks should face the morning sun, and be sheltered somewhat from the rain,” he said, “either by adding an overhanging sloped roof to keep rain from soaking the wood, or placing the blocks under the eaves of a barn, shed or house.”
When the time comes, the female bees will emerge and get to work. They’ll be looking for potential houses, so keep their options open.
“Female bees will seek a suitable nesting site near the area where they have emerged,” Zawislak said. “Once a cavity has been located, they will begin foraging nearby for pollen and nectar with which they will provision their nest. Once the eggs have been deposited, the bee will seal up the cavity. She may seek another nesting site to repeat the process.”
When prepping your garden, keep the future in mind.
“Increasing the number of suitable nesting habitats near your garden or orchard can dramatically increase the native pollinator population in your area over a few years.”
Supporting solitary bees in Arkansas
Assistant Professor of Entomology for the University of Arkansas System Division of Agriculture, Neelendra Joshi has set up solitary bee nests around Arkansas.
“I have put solitary bee nests or “bee hotels” in different locations in Arkansas,” Joshi said. “In general, these bees spend most of their time in constructing and provisioning their nest and we can help them by providing suitable nest substrates in farm landscapes.”
The importance of these bee hotels lies in their ability to encourage solitary bee populations in the state.
“In long term, this strategy would help in conservation and propagation of tunnel nesting solitary bees,” Joshi said. “In addition, these nests will help us in establishing a baseline information of solitary bees in different ecosystems.”
For more information on encouraging native bees visit www.xerces.org or www.pollinator.org.
To learn about bee keeping in your county, contact your local Cooperative Extension Service agent or visit www.uaex.uada.edu.
About the Division of Agriculture
The University of Arkansas System Division of Agriculture’s mission is to strengthen agriculture, communities, and families by connecting trusted research to the adoption of best practices. Through the Agricultural Experiment Station and the Cooperative Extension Service, the Division of Agriculture conducts research and extension work within the nation’s historic land grant education system.
The Division of Agriculture is one of 20 entities within the University of Arkansas System. It has offices in all 75 counties in Arkansas and faculty on five system campuses.
The University of Arkansas System Division of Agriculture offers all its Extension and Research programs to all eligible persons without regard to race, color, sex, gender identity, sexual orientation, national origin, religion, age, disability, marital or veteran status, genetic information, or any other legally protected status, and is an Affirmative Action/Equal Opportunity Employer.
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Media Contact: Ryan McGeeney
Communication Services
U of A System Division of Agriculture
Cooperative Extension Service
(501) 671-2120
rmcgeeney@uada.edu