What Solitary Bees can do for you and your garden
Bees pollinate 1/3 of our food supply. Why not raise solitary Spring mason bees and Summer Leafcutter bees. It’s a great way to supplement the stressed honeybee and sustain our future food supply.
The Orchard Mason Bee is the common name of a nonsocial native bee (Osmia lignaria) that pollinates spring fruit trees, flowers and vegetables. This gentle, blue-black metallic bee does not live in hives. In nature it nests within hollow stems, woodpecker drillings and insect holes found in trees or wood.. They are active for only a short period of the year. They are not aggressive and one may observe them at very close range without fear of being stung, which makes them excellent for enhancing our yards and gardens. They add beauty, activity and pollination to our plantings. They are strictly pollinators and do not produce honey. They are one of about 140 species of mason bees in North America.
All mason bees are solitary, meaning each female is a queen who does all of the chores. She can’t gather pollen/nectar, lay eggs, gather mud, AND defend her hole… so she doesn’t. The mason bee is extremely gentle.
The female mason bee carries pollen on the underside of her hairy abdomen, and then scrapes the pollen off within her nesting hole. Because the pollen is carried dry on her hair, it falls off easily as she moves among flowers, which means very successful pollination!
When the female mason bee returns to the nesting cavity she forms a small ball of pollen and nectar in the back of the nesting tube and lays an egg on the ball. She then collects mud to form a cell partition and repeats the pollen ball egg laying process until she reaches the mouth of the tube where she caps the end with mud. Interestingly, the eggs that are destined to be female are always deposited at the back of the nesting chamber; the male bees will emerge first.
Mason bee larvae hatch just a few days after the eggs are laid. They munch away on the food that’s been stored in their cell, which usually lasts them about 10 days. Then the larva spins a cocoon and pupates. By autumn, the insects look like an adult bee, but they remain inside their cocoons throughout the winter. When the weather warms in the spring, the males break through first; the females emerge several days later and the cycle begins again.
Mason bees are very effective pollinators. Just two or three females can pollinate a mature apple tree! Mason bees will also work in cool or rainy weather when honeybees are more likely to take the day off.
One Leafcutter bee can do the job of 20 honeybees! Like mason bees, they are ‘cavity nesting’. They will build cells using the pieces of leaf as lining, by overlapping segments of leaf to make a cylindrical cavity that looks a little like a cigar. Each cell is sealed up with a little segment of leaf.
The alfalfa leafcutter bee became a hero in the first half of the 20th century when it saved the declining alfalfa seed industry. A familiar story, seed production decreased when pollinating bees lost their habitats to agriculture and land clearing. This threatened a major food nutrient for livestock. Alfalfa is a source of high protein for livestock in pasture and hay mixes. Today, the alfalfa leafcutter is used extensively to pollinate this crop, and others.
Leafcutter bees, like mason bees do not have pollen baskets on their hind legs. Instead, they collect pollen on hairs on the underside of their abdomens. When the bee is carrying pollen, it is quite visible as a pale yellow color.
Its gentle nature and efficient pollination make it ideal for late summer melons, peas and other vegetables. While all leafcutter bee species are solitary, only the alfalfa leafcutter is gregarious. This means the females will nest very close together, one of the main characteristics for managed pollinators. This busy, small bee is a great summer garden addition.
Have you ever noticed neat little segments cut away from roses, lilac or other shrubs? If it’s leafcutter bees, there will be a crescent or almost circular shaped hole in the leaf. If you should find this, do not worry; usually it will not harm your plants. Almost any broadleaf deciduous plant may be used. Cultivated roses, azalea, ash, redbud and seedling maple leaves are the plants that are used most commonly in urban and suburban landscapes.
Once the leafcutter bee selects a suitable burrow the bee flies to a suitable plant to cut a round piece of leaf. This piece is rolled up and carried back to the burrow. The round piece is driven, head first into the hole and this piece serves as an end plug. The bee then returns to cut more elongate pieces, which are used to line the sides of the burrow. Once a suitable cell is lined with enough pieces of leaf, the bee collects nectar and pollen to store in the cell. After provisioning the cell, the bee lays an egg and seals the cell with another round piece of leaf. This procedure is repeated until the burrow is completely filled with cells, often four to ten cells.
Bee houses can be easily provided for your solitary bees. Many styles of homes, tubes, and reusable wooden nesting trays are available at The Bird Store and More. A south-facing garage, house, or garden shed wall are ideal areas for establishing your nesting boxes. Mount your bee houses on a wall that receives morning sun. It is best if the wall has an overhang for additional rain protection. Nesting units need to be protected from rain and wind. Keeping them mounted with the cavities tilting slightly down will prevent rainwater from entering and creating harmful mold. Securing the nesting units will also prevent movement that could dislodge eggs or young larvae. The space may only be a mere 3/8 of an inch, but the babies are too weak to crawl back in. Bee homes should be placed 5 – 7 ft above ground so you can easily watch the activity. Spring Mason Bees also need to have a source of clayey mud to pack the cells with. If you do not have clay type soil it can be easily made with an addition of clay. You only need a small hole and soil mixed with the clay. Be a kid again and make a mud pie! Place the mud on the southern wall of the hole and keep it moist. Your bees will travel about 300 feet from the nest. Make sure your bee house is located near a pollen source.
HARVESTING YOUR BEES
In the fall both Mason Bees and Leafcutter Bee cocoons can be harvested from the bee tubes and wooden trays. Store them till Spring, let them hatch and watch your garden bloom.
INTERESTING BEE FACTS:
– If a mason bee accidentally goes into another bee’s hole, the intruder will quickly back out and find the correct nest. Their individual pheromones help them identify their own hole.
– When the female is adding her final mud plug, she’ll go around and around the hole’s opening as she works to close the egg chamber.
– Using a flashlight at night or in the early morning, you can see the bees at rest in the front of their holes, with their eyes looking out at you.
– Learn to distinguish the males from the females by spotting the white hair on the males’ heads.