''Osmia xanthomelana'', the large mason bee, is a species of

mason bee Mason bee is a name now commonly used for species of bees in the genus ''Osmia'', of the family Megachilidae. Mason bees are named for their habit of using mud or other "masonry" products in constructing their nests, which are made in naturally ...

in the genus ''

Osmia Mason bee is a name now commonly used for species of bees in the genus ''Osmia'', of the family Megachilidae. Mason bees are named for their habit of using mud or other "masonry" products in constructing their nests, which are made in naturally ...

''. It has a wide distribution in the Palearctic but it is rare wherever it occurs and, for example, in

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...

it has a highly restricted distribution, although in the past it was a little more widespread there.

Description

''Osmia xanthomelana'' is a medium-sized bee, measuring 12-13mm in length with a stocky, robust structure. The main colour is black but it has golden to brown hairs which cover the face and thorax becoming sparser and paler on the abdomen.

Distribution

''Osmia xanthomelana'' is widely distributed throughout the

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

but it is apparently rare wherever it occurs. In Great Britain it is currently found only in two locations on the Llyn Peninsula, in

Gwynedd Gwynedd (; ) is a county and preserved county (latter with differing boundaries; includes the Isle of Anglesey) in the north-west of Wales. It shares borders with Powys, Conwy County Borough, Denbighshire, Anglesey over the Menai Strait, and C ...

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

Habitat

''Osmia xanthomelana'' is found around eroded cliffs of softer rocks such as clay and chalk, among landslips, dunes and in semi-natural and unimproved grassland where its food plant

bird's-foot trefoil ''Lotus corniculatus'' is a flowering plant in the pea family Fabaceae, native to grasslands in temperate Eurasia and North Africa. Common names include common bird's-foot trefoil, eggs and bacon, birdsfoot deervetch, and just bird's-foot trefo ...

occurs. To be suitable a site should also have a supply of freshwater from seepages which is needed for the bee to construct its cells for breeding.

Biology

In Great Britain male ''Osmia xanthomelana'' are recorded from April and the females are slightly later in May with both sexes being recorded up to July. The nests are usually dug out in south-east facing eroded banks, occasionally burrows from previous seasons are reused after being cleaned out by the female. The females collect freshwater from seepages around the base of the cliff to make mud which is then combined with grit to the construct the nest cells. There are normally five or six cells per nest. The cells may be stood in a cluster with their bases in the ground if a burrow is not used. The cells are each sealed with a flat lid made of the same material as they are constructed. The cells are provisioned with pollen from bird's-foot trefoil although ''O. xanthomelana'' will nectar on a variety of plants such as

horseshoe vetch ''Hippocrepis comosa'', the horseshoe vetch, is a species of perennial flowering plant belonging to the genus ''Hippocrepis'' in the family Fabaceae. Description The overall appearance depends on its habitat: sometimes it forms upright clumps ...

bramble A bramble is any rough, tangled, prickly shrub, usually in the genus ''Rubus'', which grows blackberries, raspberries, or dewberries. "Bramble" is also used to describe other prickly shrubs, such as roses (''Rosa'' species). The fruits inclu ...

and

bugle The bugle is one of the simplest brass instruments, normally having no valves or other pitch-altering devices. All pitch control is done by varying the player's embouchure. History The bugle developed from early musical or communication ...

. The wasp ''

Sapyga quinquepunctata ''Sapyga quinquepunctata'' is a species of sapygid wasp. It is a parasite of mason bees. References Sapygidae Parasitic wasps Insects described in 1781 {{Hymenoptera-stub ...

'' is known to kleptoparasitise this bee, its larvae feeding on the stored pollen.

Conservation

''Osmia xanthomelana'' was known from around 28 scattered sites in Great Britain as far north as

Tyneside Tyneside is a built-up area across the banks of the River Tyne in northern England. Residents of the area are commonly referred to as Geordies. The whole area is surrounded by the North East Green Belt. The population of Tyneside as published i ...

but it was thought to have been reduced to a single site on the

Isle of Wight The Isle of Wight ( ) is a county in the English Channel, off the coast of Hampshire, from which it is separated by the Solent. It is the largest and second-most populous island of England. Referred to as 'The Island' by residents, the Isle of ...

by the 1990s, from which no bees have been recorded since the 1990s. However, two sites were discovered on the

Llŷn Peninsula The Llŷn Peninsula ( cy, Penrhyn Llŷn or , ) extends into the Irish Sea from North West Wales, south west of the Isle of Anglesey. It is part of the historic county of Caernarfonshire, and historic region and local authority area of Gwynedd. Mu ...

in Wales in 1998 and 1999. It is thought that individual sites can be lost due to erosion and sudden landslips and this is what destroyed the Isle of Wight site. The forage plant of ''O. xanthomelana'', bird's-foot trefoil, is sensitive to over or under grazing and these can result in the loss of the plants during the colony cycle of the bee. It is also thought that climate change and agricultural run-off from nearby intensive farmland are also threats to the bee populations. Conservation measures have included clearing invasive vegetation from banks and the creation of new banks.

References

External links

List of SpeciesWorldwide Species MapPalaearctic Osmiine Bees
xanthomelana Insects described in 1802 Taxobox binomials not recognized by IUCN {{Megachilidae-stub