Mason, Mining and Leafcutter Bees

There are 77 species of Solitary bee resident in Ireland and all are excellent pollinators.  They do not live in colonies like honeybees or bumblebees.  Instead of egg-laying queens in hives solitary bees have females that mate, lay eggs and build nurseries.

If you erect a solitary bee nursery like the one in the picture facing South or South-East and at least a metre from the ground, you may attract the Mason bees (Megachile spp.) or the Leafcutter bees (Megachile spp.) (1) The entrance holes to the cavities should be without splinters and between 2mm and 10mm in diameter to cater for different species. These bees collect pollen and nectar and leave little cakes of this mixture in the cavities for their larvae.  They then deposit an egg on each cake.  Leafcutter bees seal each chamber and the entrance with a piece of leaf.  (Look at rose leaves and you will often see little discs cut out by these bees). (2)  Mason bees seal each chamber and entrance with mud. (3)  When the eggs hatch the grubs eat the pollen and nectar. (4) After a number of days, they turn into pupae and remain thus over winter before emerging in spring.  Males coming first so as not to interbreed with the females.

Mason, Mining and Leafcutter Bees 1 1e Solitary bee nursery 1
Solitary bee nursery (1)
Mason, Mining and Leafcutter Bees 2 2 Leafcutter bee with petal 2 Credit Elaine Dunne
Leafcutter bee with petal (2) Credit Elaine Dunne

These solitary bee nurseries are often called bee or bug hotels, but they are not hotels and they do not cater for bugs. (“Bug” is a term often applied to insects and other invertebrates in general.  A bug, however, is only one kind of insect-one with a sucking mouthpart).  This box is for rearing young bees. It should be brought into a cool, dry shed in October to keep it dry and re-positioned in March.  They should be cleaned regularly after use.

Mason, Mining and Leafcutter Bees 3 3e Entrances sealed with dry mud 3
Entrances sealed with dry mud (3)
Mason, Mining and Leafcutter Bees 4 4ae Chambers filled with pollen nectar and grubs 4a
Chambers filled with pollen, nectar and grubs (4a)

Mining bees (Andrena spp.), the commonest species of solitary bee in Ireland do not use nursery boxes.   They excavate tunnels in sunny banks of sand or soil in May in which the females lay eggs in food-laden cells (4) like the ones already mentioned.  These will emerge to produce broods of their own in July.

Mason, Mining and Leafcutter Bees 5 4be Chambers filled with pollen nectar and grubs 4b
Chambers filled with pollen, nectar and grubs (4b)
Mason, Mining and Leafcutter Bees 6 5a Mining bee5a Credit Elaine Dunne
Mining bee (5a) Credit Elaine Dunne
Mason, Mining and Leafcutter Bees 7 5be Mining bee tunnels 5b Credit Elaine Dunne
Mining bee tunnels (5b) Credit Elaine Dunne

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