''Osmia caerulescens'', the blue mason bee, is a species of solitary bee from the family

Megachilidae Megachilidae is a cosmopolitan family of mostly solitary bees. Both that their pollen-carrying structure (called a ''scopa'') is restricted to the ventral surface of the abdomen (rather than mostly or exclusively on the hind legs as in other b ...

. It has a

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical region ...

distribution extending into the

Indomalayan The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South and Southeast Asia and into the southern parts of East Asia. Also called the Oriental realm by biogeographers, Indomalaya spreads all over the Indi ...

region, although its presence in the

Nearctic The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America t ...

may be due to human assisted introduction.

Description

Females ''Osmia caerulescens'' are 10–11 mm in length, they are dark blue-black bees with a metallic sheen, which are sparsely covered with brown hairs with those on the abdomen forming a narrow, dense, flattened band on the hind margin of each of the segments. The dense brush of pollen collecting scopae on the underside of the abdomen is jet black. The males are slightly smaller, 9mm, more slender in build, distinctly metallic green and clothed with pale hairs.

Habitat

''Osmia caerulescens'' occurs in a wide variety of habitats, including woodland and private gardens.

Biology

''Osmia caerulescens'' uses a variety of preexisting cavities for nesting in such as insect burrows in dead wood and drilled borings in wooden blocks; hollow stems, drilled borings in pithy stems or burrows created by other insects in the ground; insect burrows in the ground, abandoned cells in exposed nests of other

aculeate Aculeata is a subclade of Hymenoptera containing ants, bees, and stinging wasps. The name is a reference to the defining feature of the group, which is the modification of the ovipositor into a stinger. However, many members of the group cannot ...

s, cavities in banks, holes and crevices in walls and glass tubes. The cell partitions and the nest plug are made of masticated leaf material and sometimes chewed petals are used as well. Any irregularities in the nest burrows are lined with leaf pulp. In larger cavities, the cells are irregularly arranged and the cell walls are partially or wholly built of chewed leaves. The bees winter as diapausing adults in their intact cocoons. 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 ...

and

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

this bee is

bivoltine Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is most often applied to insects, and is particularly in use in sericulture, where silkworm varieties vary in their voltinism. ...

and is partially so in the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

The males usually emerge first and wait around the nests seeking females to mate with and are active for about three weeks. The two flight periods in Great Britain are from mid April or May to late July, and then again in August. The bee is polylectic, but it collects pollen nearly exclusively on members of the

Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

. It has been observed collecting pollen from ''

Coronilla The genus ''Coronilla'' contains 8 species of flowering plants native to Europe and North Africa. It cointained about 20 species before being split into ''Securigera''. Species include: * ''Coronilla coronata'' * ''Coronilla juncea'' * ''Coron ...

'', ''

Hippocrepis ''Hippocrepis'' is a genus of flowering plants in the family Fabaceae. Etymology The name "Hippocrepis" comes from the Greek for "horse" () and for "shoe" (): literally, "horseshoe"; this is descriptive of the shape of the fruit segments in ...

'', '' Lotus'', ''

Medicago ''Medicago'' is a genus of flowering plants, commonly known as medick or burclover, in the legume family (Fabaceae). It contains at least 87 species and is distributed mainly around the Mediterranean basin. The best-known member of the genus is ...

'', ''

Melilotus ''Melilotus'', known as melilot, sweet clover, and kumoniga (from the Cumans),Bulgarian Folk Customs, Mercia MacDermott, pg 27 is a genus in the family Fabaceae (the same family that also includes the ''Trifolium'' clovers). Members are known ...

'', ''

Onobrychis __NOTOC__ ''Onobrychis'', the sainfoins, are a genus of Eurasian perennial herbaceous plants of the legume family (Fabaceae). Including doubtfully distinct species and provisionally accepted taxa, about 150 species are presently known. The Flora ...

'', ''

Trifolium Clover or trefoil are common names for plants of the genus ''Trifolium'' (from Latin ''tres'' 'three' + ''folium'' 'leaf'), consisting of about 300 species of flowering plants in the legume or pea family Fabaceae originating in Europe. The genus h ...

'' and ''

Vicia ''Vicia'' is a genus of over 240 species of flowering plants that are part of the legume family (Fabaceae), and which are commonly known as vetches. Member species are native to Europe, North America, South America, Asia and Africa. Some other ...

''. It has also been observed to collect pollen from some members of the

Lamiaceae The Lamiaceae ( ) or Labiatae are a family of flowering plants commonly known as the mint, deadnettle or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil, mint, rosemary, sage, savory ...

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

Brassicaceae Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The le ...

Hypericaceae Hypericaceae is a plant family in the order Malpighiales, comprising six to nine genera and up to 700 species, and commonly known as the St. John's wort family. Members are found throughout the world apart from extremely cold or dry habitats. '' ...

and

Ranunculaceae Ranunculaceae (buttercup or crowfoot family; Latin "little frog", from "frog") is a family of over 2,000 known species of flowering plants in 43 genera, distributed worldwide. The largest genera are ''Ranunculus'' (600 species), ''Delphinium' ...

The scopae of the females are used to comb pollen from the nototribic

anther The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

s of Lamiaceae and Antirrhineae. Occupied cocoons of the sapygid 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 ...

'' have been recovered from a nest of ''Osmia caerulescens'' and the

Natural History Museum, London The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum an ...

has specimens of ''S. quinquepunctata'' which have been reared from the nests of ''O. caerulescens''.

Subspecies

There are two recognised subspecies of ''Osmia caerulescens. *''Osmia caerulescens caerulescens'' (Linnaeus, 1758) is found in Europe. *''Osmia caerulescens cyanea'' (Fabricius, 1793) is from North Africa.

Distribution

''Osmia caerulescens'' is mainly Palearctic and is found over most of Europe and Asia, the Middle East and North Africa. In Great Britain it is mainly found in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

and

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 ...

becoming more localised in the north and reaches central

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...

. It is also found in

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. The occurrence of ''O.cearulescens'' in North America may be the result of introduction by humans. Its North American range is from Minnesota to Nova Scotia, south to Illinois and North Carolina.

References

{{Taxonbar, from=Q2388784 caerulescens Hymenoptera of Europe Hymenoptera of North America Bees described in 1758 Taxa named by Carl Linnaeus