Cornish mining… by bees

During my daily walks throughout the April 2020 coronavirus lockdown, I’ve been noticing new round holes on bare earth paths, with little piles of soil around them, as if something very small has been drilling into the ground.

I’ve seen the occupants going in and out in past summers – and they were one of the 100 or more species of mining bees. Mining bee holes are sometimes found together in groups, depending on the species. You are most likely to find them in your garden in spring. Up to 60cm in depth, the tunnels branch off underground, with a chamber for each individual egg, which is laid on a clump of nutritious pollen.

The stings of these gentle bees are unlikely to penetrate human skin, so sit back and enjoy their company.

One of the earliest mining bees to emerge is the hairy-footed flower bee. My brother spotted them in his London garden last week and wondered where they were nesting. I suggested the nearby (currently abandoned) private golf course, as they like bare ground and banks (as in golf bunkers). However, they may also be found nesting in walls.

You can help mining bees by leaving earth banks and patches of soil available in sunny places, by using no pesticides whatsoever in your garden, and importantly, by growing a wide variety of flowering plants to feed bees through as much of the year as possible. In mild Cornwall this can mean year-round flowers in your garden. Don’t forget flowering bushes and trees. For suggestions, see how to attract bumblebees to your garden.

Pictured here are the holes of one of the latest mining bees to fly in autumn, the ivy bee (Colletes hederae).

Best friends of fruit growers, the mason bees

Today, inside my fruit cage (despite a chilly wind), are the most welcome and gorgeous-looking bees. Ginger and furry, but more honeybee than bumblebee-shaped, they are the amiable red mason bees (Osmia rufa), ace pollinators of fruit trees and bushes.

Pollinating is exactly what I want these bees to do. The young pear tree on our south-facing wall is already in full blossom, along with the white-, red- and blackcurrant bushes. My young grafted Tamar Valley heritage apple trees and crab apple are following close behind, with one already in full flower and the others covered in pretty posies of plump pink or red buds.

We can encourage mason bees by filling our gardens with scented flowering plants, and leaving little holes and crevices in our walls – even old nail holes will do for small species. Who is inspired by a boring, lifeless, completely blank wall or fence anyway? Apparently some mason bees nest in snail shells or woodworm holes – they are very versatile little insects. This demonstrates that even a ‘pest’ to a human (like a snail or a woodworm) is actually useful, as it can be essential to the life-cycle of our most valuable garden pollinators.

Making solitary bee homes

We can help our solitary bees by creating extra nesting opportunities. Ideal sites can easily be made by drilling holes of different sizes (between 2mm and 10mm) in existing old logs or chunks of wood. Another method is to tie bundles of hollow empty stems or carefully cut sections of old bamboo sticks and hang them up securely, inside boxes or containers, in sunny places such as walls. Fix them at a height of at least a metre above ground level and tilt them slightly downwards so they cannot fill with rainwater. The female bee lays eggs in the tubes, sealing them in with mud in the case of the mason bee, or with leaves in the case of leaf cutter bees. The bee home pictured was bought and given to me as a Christmas present.

Carpenter bees are able to tunnel into old, soft wood themselves, but they will also appreciate a free home in a human-made bee nest too.

Action: make a bee hotel

Bee health and safety note: we are advised to make sure that the drilled wood is splinter-free. We should replace bee hotels, or their hollow stem contents, every couple of years so that parasites and fungus don’t build up inside.

Get to know your bumblebees

The much-loved rounded, furry, buzzy bumblebees include the buff-tailed bumblebee (Bombus terrestris), red-tailed bumblebee (Bombus lapidarius) and common carder (Bombus pascuorum). They are wonderful to watch but can be surprising difficult to photograph, as they don’t keep still for long.

Sadly, in 2020 only seven or eight species of bumblebee are considered to be widespread across Britain. Basic ID charts can be found, to see which of the 24 or so British species you are looking at.

Cuckoo bumblebees, such as the mourning bee (Melecta albifrons) that flew into our house last week (black with distinctive small white patches on the abdomen), invade the nests of other bee species. They are found wherever there are other bumblebees. Don’t dislike them, though, as they also pollinate flowers and are part of the interconnected system that is the natural world.

Follow bumblebees back to their nests on a warm day and you might find a hidden hole amongst grass or ivy in a shady, quiet place, maybe once used by mice or voles. The tell-tale sign of a nest is simply the bees going in and out. You might find nests of the tree bumblebee (Bombus hypnorum) in bird boxes or buildings.

Social bumblebee nests could contain up to 400 individual bees. This causes some people to panic about their families being stung, but this is unlikely to be an issue. Females (queens and workers) are peaceful insects that prefer to go about their own business while ignoring us, and the male (drone) bees that congregate around nests waiting for queens to come out cannot sting at all.

Providing a home for bumblebees

I have tried making nests for bumblebees using upturned, partly buried earthenware flower pots containing chicken wire (to hold the bedding up in an airy way) and soft bedding material. This is then covered with a raised slate to let air in the top while keeping the rain out. You run a short piece of hose (with drainage holes) underground to the pot. Our bumblebees chose to ignore this set-up and nest in a quiet corner underneath a spiky Pyracantha bush, next to my birdsfoot-trefoil-filled front lawn, instead. Another favourite place was a Cornish hedge behind a shed, so my main recommendation, as I mentioned above, is to have a flowery garden with undisturbed corners. If you have had success with the flowerpot method, let us know via Cornwall Wildlife Trust’s Facebook page.

More solitary bees and honeybees

Bee, wasp or fly? You can tell little solitary bees such as Osmia rufa apart from mimics that are actually flies by looking out for their long bee antennae.

Hive-dwelling honeybees once nested in hollow trees, and I did genuinely find a hollow-tree honeybee nest when I was a child. Honeybees can be quite varied in colour from black, like the hardy Cornish Black Bee, to striped, so they are sometimes confused with common wasps. Wasps (actually very varied, but we tend to notice the yellow and black striped Vespa vulgaris) have very narrow waists and fly with their legs hanging down. Honeybees carry baskets of pollen on their hind legs. If at all possible, leave both wasps and bees be (awful pun?). They are gardeners’ friends (more from me on the benefits of wasps another time).

If you seek a home for a honeybee swarm or have other honeybee questions, the Cornish Beekeepers Association or British Beekeepers Association are a first port of call.