Osmia spinulosa (Spined Mason-bee)
A smallish mason bee that was only recently transferred from Hoplitis to Osmia. With a bright orange pollen brush below the abdomen, it rather resembles a small Osmia leaiana or Megachile centuncularis. Males are easily distinguished from other Osmia species and Hoplitis claviventris by the sharp spine arising from sternite 1 and the 10-12 tiny teeth along the hind margin of tergite 6.

O. spinulosa is widespread in chalk and limestone districts of southern England south of the Severn-Wash line and along the coast of south Wales, with isolated records as far north as Yorkshire and Cumbria. It favours unimproved chalk and limestone grassland, calcareous brownfield land and coastal habitats like dunes and vegetated shingle i.e. warm places with plentiful snails and flowers of the family Asteraceae. It can be one of the commonest bees of such habitats.

Foraging is almost exclusively from Asteraceae, especially Oxeye Daisy, Rough Hawkbit, Mouse-ear Hawkweed, Hawkweed Oxtongue, Fleabane and knapweeds. Nesting occurs in the dead shells of medium-sized snails exposed to the sun. Adults have a long flight period that extends from May until September.

BWARS account:
www.bwars.com/index.php?q=bee/megachilidae/osmia-spinulosa
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