Country Diary: Down on the floor with the solitary bees

I’m lying on my front on the moist, mossy lawn, the sun warming my back. Around me swallows are swooping in and out of the barn while dandelions, lady’s smock and cowslips attract the butterflies and bees. But down here, my attention is focused under the box hedges of my herb garden. I am watching volcanoes form. Not the sort that spew hot lava, but small cones of the gritty soil with a vent in the top about the size of my little fingernail.

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These are the entrances to the breeding burrows of the tawny mining bee, Andrena fulva. They are just one of the 240 species of solitary bees in Britain, and are just as important for pollination as the one species of honeybee. Each has different shaped mouthparts, which have evolved alongside flowers with different access routes to their nectar so that the plants are more likely to be pollinated from the same species. And you don’t have to farm the solitaries. This type needs only fine, sandy soil so they can dig deep burrows (and surprisingly quickly too with their tiny legs). They make side chambers and lay one egg in each, with a small supply of nectar and pollen. Then they’re sealed up and the larvae left to hibernate over winter, until they dig their way out the next spring.

I could never grow Mediterranean herbs such as thyme, sage, oregano, orpine or lavender in my damp garden until a few years ago, when I had this square dug out and filled with limestone hardcore. Unwittingly, I had also made the perfect place for these mining bees to breed. It also helped that this was under the bit of lawn where we once had the kids’ sandpit.

Meanwhile, the osmia mining bees – the red mason and the leafcutter bees you can buy nesting houses for in garden shops – are a different species. I was puzzled to see an osmia scrabbling against the mud-sealed doors once, as I thought it couldn’t be a predator of its own kind. A quick post on the Facebook page of the specialist Bees, Wasps and Ants Recording Society got me an answer in 10 minutes – it was the male who could “smell” the virgin female inside and was desperate to mate with her before any other.