While Honeybees are getting a great deal of attention for their plight, it might be the other bees like Mason Bees and Leafcutter Bees we should be worrying about more. Here in North America, our plants made do for millenia without the iconic honeybee. Here, there are hundreds of species of small stingless solitary bees, pollinating wasps, bumble bees and pollinating flies. Most of these native insects are smaller than honeybees and are able to fly shorter distances to find food and shelter.
Our native pollinators, the other bees, are much more susceptible to changes in their environment. Their physical size alone makes it much harder to travel to new areas to find food or nesting sites. Most native bees only fly 300 feet or less to supply their needs. Some of the smaller bees might only travel 50′ from where they are born in their entire life.
While for us this might seem a limiting factor, these bees are superior pollinators. They work at cooler temperatures than honeybees and will work in wetter weather. Mason bees only live for 3 weeks so they must be efficient in gathering the pollen they need to feed their young. They emerge in early spring, mate, gather pollen and lay eggs and die in that short 3 week period. That 3 weeks just happens to coincide with fruit tree pollination. Mason bees are 3 times more efficient at pollinating fruit trees than honeybees alone.
Leafcutter Bees begin their pollination after the Mason Bee is done. Leafcutter Bees emerge when temperatures reach 75 degrees. They live about a month but, with warm weather may have two or more generations in a summer. They are a general pollinator and are very good at pollinating garden plants. The name leafcutter comes from their cutting 3/4″ circles from leaves to seal the nest chambers for their young. Don’t be alarmed if you see these little circles cut out of leaves in the garden and certainly don’t spray for them.
The previous two bees are much talked about because we can build housing for them and have a hand in their production but there are many more pollinator bees out there. There are dozens of species of ground nesting bees that are excellent pollinators. All they need is a food source and a patch of bare ground in which to dig their nests. Some prefer sand, some garden soil, some prefer clay but all need a patch of ground that has no grass or other plant cover. They are adapted to our native grasses that are bunch grasses that leave open ground between them. Modern lawn grasses are like a carpet that leaves no place for these small bees to dig their nests. Covering a patch of ground in the garden to kill the vegetation for the following year will help these insects. Just remember not to till it up while they are nesting there.
Hole dwelling bees like Mason Bees and Leafcutter Bees are not social bees like honeybees they are solitary in that each female bee feeds and cares for her own young with no help from other bees. They are gregarious and like to nest in close proximity to one another. It looks like a community but there is no cooperation or sharing of duties.
Nesting blocks for Mason Bees and Leafcutter Bees should be mounted on something solid like a wall or panel of some sort with some shelter from rain but more important, shelter from strong winds. A small bee carying a load of pollen or mud to seal a nest does not want to fight stong winds trying to locate their nest. It is very important that the nest blocks not be moved while the bees are actively nesting in them. They are unable to adjust to the movement of their nest and will abandon their efforts if the block is moved at all. Set it up and leave it alone until the nesting season is over.
These close quarters that we create by putting out housing require us to do some occaisional housekeeping. Any large group of insects will eventually become home to diseases and parasites just like any large group of humans.
To break the cycle, every
every other year at the most, the nest blocks need to be cleaned or replaced. Any house that consists of drilled holes or bamboo tubes should be replaced. A house made of laminates that can be separated should be separated and scrubed with a bleach solution to kill any fungi or mites that may have built up.The best way to do this is to put up a new house before emergence in spring and put the old house in an emergence box which is a closed box with a 3/4″ hole in it for the bees to escape through. They will leave over the course of a few weeks and the old house can be cleaned and rehung.
Mason Bee and Leafcutter Bee cocoons can be removed from the laminates and stored in a ventilated container in a refrigerated space until spring. This allows the laminates to be cleaned and ready for the newly hatching bees. There is a market for excess cocoons.