by Joe Shorthouse
MANITOULIN – As residents of Manitoulin Island are painfully aware, the COVID-19 pandemic has caused many changes to our lifestyle. However, one positive change is that stay-at-home orders have led to a new appreciation of home gardens.
Homeowners are discovering that gardens not only provide a safe retreat from the scourges of viruses, they are great places to come in contact with nature. Having insect pollinators and birds visit our gardens has become a relaxing and educational pastime for Island residents used to social distancing, masks and remaining close to home.
Local gardeners who have been closely monitoring their flowers and vegetables over the years have likely recognized that the numbers of flower-visiting bees have decreased. As these insects play a vital role in the functioning of ecosystems, there are ways in which we can lend a helping hand and reverse this trend. We can plant more flowers rich with nectar and pollen and we can install a ‘bee hotel.’
Bee hotels are structures that provide nesting sites for solitary bees—the kinds of native bees known as sweat bees, carpenter bees, leafcutter bees and mason bees, most of which are better pollinators than the introduced honeybee.
There are about 850 species of native bees in Canada and most are solitary living in holes in the ground, in hollow stems of dead shrubs, holes in trees made by burrowing beetles, or crumbling mortar, but we can attract them to artificial nests in our yards.
‘Bee condos’ might be a better name than ‘bee hotels’ as they are not short term accommodations like a hotel room, but are permanent summer homes as several generations of bees develop in them from an egg through larval stages and then pupa and finally emerges as an adult.
Solitary bees are so-named because they make individual nest cells for their larvae. They do not live in hives as do honeybees; however, many species group their nest cells together in aggregations, like people living in an apartment building.
All solitary bees collect nectar and pollen from flowers. They are harmless to people. They are not aggressive and rarely sting unless you pinch them between your fingers. They do not have painful stings like honeybees, and if they did sting, you likely would not feel it.
Working alone, each female solitary bee diligently visits numerous flowers to collect enough pollen and nectar to feed a larva from egg to adult. She also collects building materials for her nests used to construct additional cells for each egg.
Bee hotels consist of a series of tubes or tunnels each about 15 cm long and about eight mm in diameter (about the diameter of an HB pencil). They can be purchased commercially at some hardware stores, ordered online or you can make your own. Tubes of slightly larger and small diameter should be added to the hotel as certain bees prefer different sizes.
Hollow tubes of bamboo available at hardware or garden stores are suitable or make your own by rolling brown paper around an HB pencil and pinching off one end with tape. Tubes should be closed at one end (back of the house) to stop parasites from attacking the bee larvae.
Bee hotels can be made from wood as long as you use natural, untreated wood and without chemicals such as varnish, paint or wood protectant that will repel insects. Some bees can be encouraged to nest in your garden by drilling holes in dry logs or blocks of wood. Even an empty milk carton will do as they are already waterproof. Leave the bottom intact as this will be the back of the house.
Bee hotels should have a roof with an overhang that prevents rainwater from contacting the tubes. Rainwater in the tubes causes mould, just as it does in our own homes.
The hotels should be firmed attached to a tree, a post, or your house such that they do not sway in the wind. Within hours, you will see tiny bees flying around your hotel as they take mental snapshots of various openings and explore tubes for possible nests. Many kinds of solitary bees are so small you may not recognize them as bees.
Bee hotels are best positioned in full sun, facing south or south east and at least a metre off the ground with no vegetation in front to obscure entrances to the tunnels.
Once a bee choses its home, no other bee will enter and miraculously, each bee remembers the location of their own home. Females lay one egg per cell on top of a ball of pollen stuck together with nectar. She builds a partition wall between the cells and repeats the process until the tube is full. Then she closes it with mud, leaves or fine hairs before moving on to the next tube.
If you notice round holes in the leaves of your rose bushes, do not begrudge the leaf cutter bee that made them as she took the little material to raise her family. She uses the leaves to make cells for her offspring and building partitions until the entire tunnel is full. She then builds a final, thicker wall to cap the tunnel and shortly afterwards she dies.
Mason bees, another of the solitary bees, line their nests with mud and plant fibres they collect and bring to the nest. Place a bowl of moist clay near your bee hotel which the mason bees will use for construction material.
Solitary bees can have several generations in a bee hotel over the summer, but come fall, the last generation remains inside until spring. Bring the bee hotels into a cool, dry area, such as a shed to protect them from wind and rain and then place them outside soon as the snow disappears in the spring.
Having a bee hotel to watch over the summer provides an opportunity to see how bees are part of a diverse ecosystem. However, a study in Toronto by York University entomology professor Lawrence Packer and his student Scott MacIvor found that several kinds of wasps were inhabiting the local bee hotels.
Work by the two entomologists reminded us that bees are types of wasps, just vegetarians that eat pollen and nectar rather than meat-eaters like their wasp relatives that paralyze and collect other insects to feed their young. However, the wasps living in bee hotels are not the hated yellow jackets or hornets which live in groups in paper nests and sting to protect their offspring and the queen.
Wasps that share bee hotels are also solitary and fly away at the site of humans rather than defend their homes. On the plus side, solitary wasps collect caterpillars and other insects that chomp away on vegetables, shrubs and trees. The location of bee hotels is important when attracting either bees or wasps. Place a bee hotel in the shade and it will be more favourable to wasps. Place a hotel in an area that receives the sun and more bees will inhabit it.
Having a bee hotel in our yards reminds us not to panic when we see bees and wasps and attempt to kill them. Without pollinators, there would be no berry-producing shrubs on Manitoulin Island such as hawthorn, chokecherry, cranberry or wild roses, or fruit-producing trees such as apples. Without bees, we cannot produce garden vegetables such as tomatoes, peas, beans, cucumbers and squash.
Creating space for bees and predacious wasps can become a rewarding experience that will teach us the importance of natural diversity and sustainability.
*Dr. Joe Shorthouse is a retired entomologist formerly with Laurentian University in Sudbury and a summer resident of Manitoulin Island.