I was walking the embankment alongside the Kent Estuary lLast weekend and a small black-and-yellow flying creature buzzed past me and disappeared into a hole in the ground, in the middle of a small mound of loose soil.

Its tail was still visible but only just, so I couldn’t identify it for sure, but it was probably a mining bee of some kind. This got me thinking about solitary bees and their role in pollination.

There are about 250 types of solitary bee in the UK, most of which nest in the ground; either digging their own burrows or using old beetle holes. Several others make holes in the stems of plants such as thistles or brambles (the blue carpenter bee) or even shelter in empty snail shells (the bi-coloured mason bee, the female of which may only lay a dozen eggs in her lifetime). This last fascinates me: she will lay her eggs in separate cells in a disused snail shell, seal the entrance with chewed up leaves then turn it to face the ground, and camouflage it with grass stems or chewed up leaves! That’s pretty cool for a tiny insect on her own.

About a quarter of our solitary bees are cuckoo bees: like the bird which is their namesake, they lay their eggs in other bees’ nests and their larvae kill those of the host, either directly, or simply by eating their food.

We call them solitary bees because each female lays eggs in her own nest or nests, but it’s common to find several nests in close proximity – just because that area is a good nesting site, or they’re near a good food source. They’ll only really “socialise” during mating.

Solitary bees are efficient and important pollinators; they collect their pollen on ‘scopa’, stiff, branched hairs on their legs or under their abdomen. As the female solitary bee collects pollen, she packs it onto her scopa less carefully and without the addition of saliva to moisten it. This means it’s far more likely to fall off when the bee visits the next flower.

Solitary bees also carry less pollen in each load, so need to make many more trips back and forth from the flowers to their nests than honeybees and bumblebees. These extra foraging trips mean that many more flowers get pollinated in the process. Because of this, solitary bees are estimated to be up to 115% more effective in transferring pollen than honeybees.

Some species are specialists: they pretty much exclusively go to certain plant families, usually daisies or peas, which makes them really important to those plants – and thus to us if we’re growing them as food crops or in our gardens. Species such as the tawny mining bee are recognised as a first-rate pollinator of orchard crops such as cherry, pear and apple.

You can encourage solitary bees in your garden both by planting suitable plants, and providing good nesting opportunities: don’t be too tidy, and make sure there are some woody-stemmed weeds for carpenter bees to use. Mason bees like cavities in walls, so leave your stone walls un-pointed so they can get in, and maybe leave piles of rocks in corners, or even invest in a commercially available artificial nest product. Don’t panic if you see a bee disappear into a hole in your lawn – no solitary bee will sting unless it feels really threatened, and they’re definitely going to be a good thing for your flowers and crops. Like so much of our wildlife, tThey need all the help they can get.

You can get involved and help create really important records by reporting sightings of solitary bees on Cumbria Wildlife Trust’s website using our quick link - just click here.