Nick Upton / Red mason bees (Osmia bicornis) entering and leaving nest hole drilled into a log within an insect hotel, Gloucestershire, England, UK, April.

Kim Taylor / Red mason bee (Osmia rufa) female in flight carrying mud to nest, Surrey, UK, April

Colin Monteath / Sunset from sand dunes above Mason Bay Beach, Rakiura National Park, Stewart Island, New Zealand

Konrad Wothe / Yellowjacket (Paravespula vulgaris) wasp feeding on fruit, Germany

Phil Savoie / Red mason bee (Osmia bicornis) female bee bringing in pollen load under her abdomen for brood cell, Monmouthshire, Wales, UK, May.

Phil Savoie / Red mason bee (Osmia bicornis) male at bee hotel. Monmouthshire, Wales, UK. May.

Phil Savoie / Red mason bee (Osmia bicornis) female bee bringing in pollen load under her abdomen for brood cell Monmouthshire, Wales, UK, May..

Phil Savoie / Red mason bee (Osmia bicornis) female bee sealing off brood cells with mud Monmouthshire, Wales, UK. May.

Phil Savoie / Red mason bee (Osmia bicornis) female bee bringing in pollen load under her abdomen for brood cell Monmouthshire, Wales, UK. May.

Phil Savoie / Red mason bee (Osmia bicornis) female bee sealing off brood cells with mud Monmouthshire, Wales, UK. May.

Phil Savoie / Red mason bee (Osmia bicornis) female bee bringing in pollen load for brood cell Monmouthshire, Wales, UK, May.

Phil Savoie / Red mason bee (Osmia bicornis) female bee capping off nest brood cell with mud, Monmouthshire, Wales, UK. May.

Phil Savoie / Red mason bee (Osmia bicornis) female bee being followed by male Monmouthshire, Wales, UK. May.

Phil Savoie / Red Mason bee (Osmia bicornis) female nectar robbing from comfrey, Comfrey (Symphytum officinale), Monmouthshire, Wales, UK. May

Phil Savoie / Red mason bee (Osmia bicornis) female bee bringing in pollen load under her abdomen for brood cell Monmouthshire, Wales, UK. May

Phil Savoie / Red mason bee (Osmia bicornis) female bee bringing in pollen load under her abdomen for brood cell, Monmouthshire, Wales, UK. May

Phil Savoie / Red mason bee (Osmia bicornis) female bee capping off nest brood cell with mud, Monmouthshire, Wales, UK. June

Phil Savoie / Red mason bee (Osmia bicornis) female bee being followed by male, Monmouthshire, Wales, UK. May

Phil Savoie / Red mason bee (Osmia bicornis) feeding on Chive (Allium schoenoprasum), Monmouthshire, Wales, UK. July

Phil Savoie / Red mason bee (Osmia bicornis) female bee bringing in pollen load under her abdomen for brood cell in bee hotel. Monmouthshire, Wales, UK. May.

Alan Williams / Blue mason bee (Osmia caerulescens) resting on brick wall in garden. Cheshire, England, UK. June.

Alan Williams / Red mason bee (Osmia bicornis) female sealing entrance to nest hole in bee nesting box. On wall of house, Cheshire, England, UK. May.

Karine Aigner / Mexican free-tailed (Tadarida brasiliensis) bats emerge from the Eckert James River Bat Cave Preserve bat cave in Mason, Texas, USA. July 2015.

Rod Williams / Red mason bee (Osmia bicolor) male feeding on Green alkanet (Pentaglottis sempervirens) Beverley Court Gardens, Lewisham, London, England, UK. April.

Rod Williams / Blue mason bee (Osmia caerulescens) at the entrance to its nest-hole, Brockley Cemetery, Lewishaam, London, England, UK. May.

Rod Williams / European potter wasp (Ancistrocerus gazella) Sutcliffe Park Nature Reserve, Eltham, London, England, UK. August.

Fabrice Cahez / Two colour mason bee (Osmia bicolor) Vosges, France, March.

Andy Sands / Two coloured mason bee (Osmia bicolor) collecting leaf mastic to seal nest in old snail shell, Bedfordshire, England, UK, June

Andy Sands / Two coloured mason bee (Osmia bicolor) collecting leaf mastic to seal nest in old snail shell, Bedfordshire, England, UK, June

Andy Sands / Mason wasp (symmorphus gracilis) on sandy bank of old quarry, Oxfordshire, England, UK, August

Phil Savoie / Spined mason bee (Osmia spinulosa) female visiting yellow composite flower, Monmouthshire, Wales, UK, June.

Phil Savoie / Spined mason bee (Osmia spinulosa) female visiting yellow composite flower, Monmouthshire, Wales, UK, June.

Phil Savoie / Red mason bee (Osmia bicornis) visiting Geranium sp flower, Monmouthshire, Wales, UK, May.

Phil Savoie / Red mason bee (Osmia bicornis) female feeding on Cotoneaster flowers, (Cotoneaster sp.) Monmouthshire, Wales, UK, May.

Phil Savoie / Red mason bee (Osmia bicornis) basking, Monmouthshire, Wales, UK, May.

Phil Savoie / Red mason bee (Osmia bicornis) basking, Monmouthshire, Wales, UK, May.

Phil Savoie / Red mason bee (Osmia bicornis), female flying to hardy Geranium flower, Monmouthshire, Wales, UK. May.

Rod Williams / Red mason bees (Osmia bicolor) Mating pair Beverley Court Gardens, Lewisham, London, England, UK April.

Phil Savoie / Red mason bee (Osmia bicornis) pollinating Chive (Allium schoenoprasum) Wales, UK. June.

Phil Savoie / Red mason bee (Osmia bicornis) pollinating Chive (Allium schoenoprasum) Wales, UK. June.

Phil Savoie / Red mason bee (Osmia bicornis) pollinating Chive (Allium schoenoprasum) Wales, UK. June.

Phil Savoie / Red mason bee (Osmia bicornis) feeding on Common dandelion (Taraxacum officinale) flowers, Monmouthshire, Wales, UK, May.

Phil Savoie / Red mason bee (Osmia bicornis) flying to Bluebell (Hyacinthoides non-scripta) flower, Monmouthshire, Wales, UK, April.

Phil Savoie / Red mason bee (Osmia bicornis) flying to flower, Green alkanet (Pentaglottis sempervirens), Monmouthshire, Wales, UK, April.

Phil Savoie / Red mason bee (Osmia bicornis) feeding on Green alkanet (Pentaglottis sempervirens), Monmouthshire, Wales, UK, April.

Phil Savoie / Red mason bee (Osmia bicornis) nesting in wall, Monmouthshire, Wales, UK, April.

Philippe Clement / European orchard bee (Osmia cornuta) emerging from its nest in an insect house, Belgium, March

John Waters / Timelapse of Red mason bees (Osmia rufa) outside a bamboo bug box, Somerset, England, UK. May.

Nick Upton / Insect hotel with drilled logs and bundles of bamboo stems, some with partially completed mud nests of Mason wasps wasps (Ancistrocerus sp), garden, Gloucestershire, UK, May.

Alan Williams / Red mason bee (Osmia bicornis) male feeding on Thyme (Thymus sp) flowers in garden. Cheshire, UK, April.

James Dunbar / Female red mason bee (Osmia bicornis) gathering pollen from a Buttercup (Ranunculus) flower, Bristol, England, UK, May.

James Dunbar / Female red mason bee (Osmia bicornis) collecting mud to build her nest, Bristol, England, UK, June.

James Dunbar / Red mason bees (Osmia Bicornis) mating on a Dandilion (Taraxacum) flower, Bristol, England, UK, May. Captive.

James Dunbar / Female red mason bee (Osmia bicornis) depositing nectar and pollen into a cell for her offspring, Wales, UK, June.

James Dunbar / Female red mason bee (Osmia bicornis) depositing nectar and pollen into a cell for her offspring, Wales, UK, June.

Andy Sands / Blue mason bee (Osmia leaiana) pushing pollen from Fleabane flower into scopa - pollen gathering hairs on abdomen, Oxfordshire, England, UK, August

Andy Sands / Blue mason bee (Osmia leaiana) gathering pollen from Fleabane flower, Oxfordshire, England, UK, August

Andy Sands / Mason wasp (Symmorphus gracilis) collecting mud for nest building, Oxfordshire, England, UK, September

Andy Sands / Two coloured mason bee (Osmia bicolor) Bee manouvering old snail shell to nest in, Bedfordshire, England, UK, June

Andy Sands / Two coloured mason bee (Osmia bicolor) carrying dead grass to cover nest in old snail shell, Bedfordshire, England, UK, June

Andy Sands / Two coloured mason bee (Osmia bicolor) Bee covering nest in old snail shell with dead grass, Bedfordshire, England, UK, June

Andy Sands / Two coloured mason bee (Osmia bicolor) carrying dead grass to cover nest in old snail shell, Bedfordshire, England, UK, June

MYN / Clay Bolt / Mason bee (Heriades sp) South Carolina, USA Meetyourneighbours.net project

Clay Bolt / Mason bee (Chelostoma philadelphi) male, captured by an Ambush bug (Phymata sp) that lies hidden in a mock orange (Philadelphus sp) blossom. South Carolina, USA. May.

Chris Shields / Red mason bee (Osmia rufa) illustration

Chris Shields / Red mason bee (Osmia rufa) female, illustration

Chris Shields / Western mason bee (Osmia parietina) illustration

Chris Shields / Large mason bee (Osmia xanthomelana) illustration

John Abbott / Four-toothed mason wasp (Monobia quadridens), Tuscaloosa County, Alabama, USA Controlled conditions. September

Nick Upton / Gold-fringed mason bee (Osmia aurulenta) nectaring on Rock rose (Cistus pulverulentus) in a garden planted with pollinator attracting flowers, Dungeness, Kent, UK. June.

Nick Upton / Blue mason bee (Osmia leaiana) nectaring on Common knapweed (Centaurea nigra) in a perennial wildflower meadow planted on an urban common by Bristol University's Urban Pollinators project, Horfield, B...

Rod Williams / Red mason bee (Osmia bicolor) Brockley, Lewisham, London. May.

Andy Sands / Blue mason bee (Osmia leaiana) male basking below bamboo tube in bee hotel having recently emerged, garden, Hertfordshire, England, UK, May

Andy Sands / Mason wasp (Ancistrocerus gazella) dormant in flower during cold weather conditions, Surrey, England, UK, June

Andy Sands / Blue mason bee (Osmia leaiana) nectaring from knapweed flower, Surrey, England, UK, June

Andy Sands / Heath potter wasp (Eumenes coarctatus) female using her mandibles to collect mud for nest building, Surrey, England, UK, August

Andy Sands / Mason wasp (Ancistrocerus scoticus) female collecting mud to build nest, Cornwall, England, UK, September

Andy Sands / Heath potter wasp (Eumenes coarctatus) female using her mandibles to collect mud for nest building, Surrey, England, UK, August

Andy Sands / Two coloured mason bee (Osmia bicolor) bee that nests in old snail shells and then carries bits of twig or vegetation to cover the shell, Buckinghamshire, England, UK, June

Andy Sands / Heath potter wasp (Eumenes coarctatus) female using her mandibles to collect mud for nest building, Surrey, England, UK, August

Andy Sands / Heath potter wasp (Eumenes coarctatus) female using her mandibles to collect mud for nest building, Surrey, England, UK, August

Andy Sands / Blue mason bee (Osmia leaiana) female, scopa packed with pollen, in flight returning to nest in bamboo tube in bee hotel, garden, Hertfordshire, England, UK, June

Andy Sands / Parasitic fly (Cacoxenus indigator) laying eggs into nest of Red mason bee (Osmia bicornis) in garden bee hotel / insect box . Hertfordshire, England, UK, May

Andy Sands / Parasitic fly (Cacoxenus indigator) laying eggs into nest of Red mason bee (Osmia bicornis) in garden bee hotel / insect box Hertfordshire, England, UK, May

Andy Sands / Two coloured mason bee (Osmia bicolor) bee that nests in old snail shells and then carries bits of twig or vegetation to cover the shell, Buckinghamshire, England, UK, June

Pascal Pittorino / European potter wasp (Ancistrocerus gazella) feeding on Ivy flowers (Hedera helix) in a garden, Toulon, Var, France, October

Nick Upton / Red mason bee (Osmia rufa) male wating for females to emerge from nest holes in a drilled log within an insect hotel, Gloucestershire garden, UK, April.

Nick Upton / Red mason bee (Osmia rufa) male wating for a female to emerge from a nest hole in a drilled log within an insect hotel, Gloucestershire garden, UK, April.

Nick Upton / Mason wasp / Potter wasp (Ancistrocerus sp.) inspecting a nest hole in a drilled log within an insect hotel, Gloucestershire garden, UK, April.

Nick Upton / Red mason bee (Osmia rufa) female emerging from her nest hole in a drilled log within an insect hotel after provisioning a brood cell with pollen, Gloucestershire garden, UK, April.

Alex Hyde / Heath potter wasp (Eumenes coarctatus) nest, Dorset, UK. August.

Philippe Clement / Red mason bee (Osmia bicornis / Osmia rufa) infested with Hairy-footed mites (Chaetodactylus) Belgium, April

Pascal Pittorino / European potter wasp (Ancistrocerus gazella) on Wood sorrel flower (Oxalis articulata), Toulon, Var, Provence, France, October.

James Dunbar / Red Mason Bee. (Osmia bicornis) male grooming. Bristol, England, UK. Captive.

Andy Sands / Blue mason bee (Osmia caerulescens) male recently emerged warming up in sunshine on garden rockery stone, Hertfordshire, England, UK. April

Andy Sands / Blue mason bee (Osmia caerulescens) male emerging from bee hotel or insect box in garden, Hertfordshire, England, UK. April