To Bee Or Not To Bee, A Home For The Red Mason Bee

Late March to early April, when the dandelions flower en masse, is the time for Red Mason Bees to appear.  They will feed on many of the other flowers for the next 12 weeks, playing a major role pollinating fruit orchards, but dandelions are a favourite.

The Red Mason is smaller than a Honeybee with a black head and an abdomen covered in distinctive fox-red hairs.  These are used to collect pollen.

Although classed as a solitary bee because each female chooses and provisions its own nest, if good nest sites are found together, then females will nest alongside each other.

The nests are in tubular holes such as hollow plant stems or cracks in walls.  They are called Mason Bees because they use clay to line and adapt their nest tubes.  Their close relatives, the Leaf-cutter Bees use pieces of leaf.  They are not Mining Bees which dig their own holes in bare soil or cliffs.

Red Mason Bees can be encouraged to live in your garden by providing them with an artificial nest site.  Unfortunately, many of the nest kits for sale are good for hibernating and other species of breeding insects, but are not suitable for Red Mason Bee breeding.

A nest site needs to be a sunny position facing south or south west and not shaded by overhanging branches.  It should be at least three quarters of a metre above ground but preferably higher and also on a solid foundation, not on a moving branch.  A suitable place would be under the eaves of a shed or summer house.  If part of a larger bug hotel e.g. made from old pallets or as part of a log pile then they should be at the top.

As with the usual bug hotels, a bundle of tubes of the appropriate length and diameter can be encased in a wooden box.  The individual tubes can be made from lengths of hollowed garden cane or plant stems from last year, such as teasel or agapanthus, or recycled plastic.  The tubes should be 16cm long to allow the back ends to be plugged.

One of the most overlooked considerations is the depth of the tubes.  These need to have a clear 15cm or 6 inches depth.  A quirk of the nesting behaviour means any less will produce an imbalance of too many male bees.  

When the female finds a nest burrow or tube, she blocks the far end with clay and lines the rest of the burrow with clay to the correct diameter.  Eight eggs are laid in turn from the back of the tube out to the mouth, each on a bed of pollen softened with nectar and separated from the next by a clay partition. 

The deepest four eggs will become males and the four nearest the entrance will be females.  If the tube is too short, it will have the four male eggs but there will not be room for four females and fewer females is not good for the long term survival of the species.

The width of the tubes is important, they should be 8mm.  If a little larger the female will narrow it down with clay. If smaller then it will be no use for the Red Mason but there are two other related species that may use it.

Once the nest box is in place, a clay plug at the entrance to a tube indicates that it has been used.  

The larvae pupate in a cocoon in the tube to overwinter so the whole kit can be moved into a shed after September as protection from the weather and then brought out again in mid March.  

The males always emerge first, the furthest one in chewing through the first partition and deliberately nipping their brother on the bum.  This continues along the tube until the last female lets them all out of the entrance.

Hopefully this happens on a nice warm, dandelion filled day for them all to get over the shock!

Mick Street writes for the Sid Valley Biodiversity Group

Late March to early April, when the dandelions flower en masse, is the time for Red Mason Bees to appear.  They will feed on many of the other flowers for the next 12 weeks, playing a major role pollinating fruit orchards, but dandelions are a favourite.

The Red Mason is smaller than a Honeybee with a black head and an abdomen covered in distinctive fox-red hairs.  These are used to collect pollen.

Although classed as a solitary bee because each female chooses and provisions its own nest, if good nest sites are found together, then females will nest alongside each other.

The nests are in tubular holes such as hollow plant stems or cracks in walls.  They are called Mason Bees because they use clay to line and adapt their nest tubes.  Their close relatives, the Leaf-cutter Bees use pieces of leaf.  They are not Mining Bees which dig their own holes in bare soil or cliffs.

Red Mason Bees can be encouraged to live in your garden by providing them with an artificial nest site.  Unfortunately, many of the nest kits for sale are good for hibernating and other species of breeding insects, but are not suitable for Red Mason Bee breeding.

A nest site needs to be a sunny position facing south or south west and not shaded by overhanging branches.  It should be at least three quarters of a metre above ground but preferably higher and also on a solid foundation, not on a moving branch.  A suitable place would be under the eaves of a shed or summer house.  If part of a larger bug hotel e.g. made from old pallets or as part of a log pile then they should be at the top.

As with the usual bug hotels, a bundle of tubes of the appropriate length and diameter can be encased in a wooden box.  The individual tubes can be made from lengths of hollowed garden cane or plant stems from last year, such as teasel or agapanthus, or recycled plastic.  The tubes should be 16cm long to allow the back ends to be plugged.

One of the most overlooked considerations is the depth of the tubes.  These need to have a clear 15cm or 6 inches depth.  A quirk of the nesting behaviour means any less will produce an imbalance of too many male bees.  

When the female finds a nest burrow or tube, she blocks the far end with clay and lines the rest of the burrow with clay to the correct diameter.  Eight eggs are laid in turn from the back of the tube out to the mouth, each on a bed of pollen softened with nectar and separated from the next by a clay partition. 

The deepest four eggs will become males and the four nearest the entrance will be females.  If the tube is too short, it will have the four male eggs but there will not be room for four females and fewer females is not good for the long term survival of the species.

The width of the tubes is important, they should be 8mm.  If a little larger the female will narrow it down with clay. If smaller then it will be no use for the Red Mason but there are two other related species that may use it.

Once the nest box is in place, a clay plug at the entrance to a tube indicates that it has been used.  

The larvae pupate in a cocoon in the tube to overwinter so the whole kit can be moved into a shed after September as protection from the weather and then brought out again in mid March.  

The males always emerge first, the furthest one in chewing through the first partition and deliberately nipping their brother on the bum.  This continues along the tube until the last female lets them all out of the entrance.

Hopefully this happens on a nice warm, dandelion filled day for them all to get over the shock!

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