Solitary Bees in Scottish Gardens

Solitary Bees can't be bought. The way to get more in the garden is to create the right conditions, and here's how.

What does it look like?

Solitary bees are a far more varied group than bumblebees or the single honeybee species: over 250 British species, ranging from 5mm to over 15mm long, and no single description covers them. Mining bees (Andrena, around 65 British species) nest in the soil and are behind the small volcano-shaped spoil heaps sometimes found in lawns in spring, most often from the tawny mining bee, bright foxy-red and common in gardens; the ashy mining bee is black with two broad grey bands. Mason bees (Osmia, 11 species) build nests sealed with mud in hollow stems, old masonry and other cavities; the red mason bee is Britain's most familiar solitary bee generally, but genuinely uncommon in Scotland and Ireland. Leafcutter bees (Megachile, 7 species) cut neat semicircles from leaves to line their nest cells, needing up to 40 leaf pieces for just one cell. Sweat bees (Lasioglossum and Halictus, around 40 species) are small, often metallic, ground-nesting bees. The wool carder bee scrapes downy plant hairs to build its nest; unusually for a solitary bee, its females emerge before the much larger, territorial males. All female solitary bees can sting, but they're not aggressive and only do so if handled roughly.

Life cycle

There's no worker caste and no colony: each female builds and provisions her own nest alone, then dies before the next generation emerges the following year, so there's no queen surviving to start again either. Ground-nesting species can still be gregarious, with many individual nests packed close together even though each female works alone. Most species are active for a single flight period in spring or summer rather than year-round.

How to encourage it

Fill a garden with nectar- and pollen-rich flowers through as much of the year as possible, the same starting point as any pollinator. Some solitary bee species are specialists, provisioning their nest with pollen from just one plant or plant family, so a few specific choices genuinely make a difference beyond general flower cover.

Many species nest in bare or lightly vegetated soil, so leave some patches of ground uncovered rather than mulching or planting every inch; a small sandy patch of lawn sprouting volcano-shaped spoil heaps in spring is a mining bee nest, not lawn damage, and is gone again within a few weeks. Others use hollow plant stems, old beetle holes in dead wood, or crumbling mortar in old walls: leaving some of these features in place, rather than tidying them all away, is itself a form of encouragement. A purpose-built bee hotel genuinely attracts leafcutter and mason bees: pack untreated hollow stems, bramble, reed or bamboo, cut to fit a simple wooden frame, mixing hole diameters from 2-10mm with plenty at the bees' preferred 3-5mm, discarding any bent or knobbly ones. Hang it on a sunny wall sheltered from rain, and clean it once a year to remove built-up fungi, debris and parasites.

Avoid pesticides wherever possible, and never spray a flower that's open, since that's exactly when a pollinator is likely to be on it.

Plant these to help:

• Willow: an early-spring nectar source for several mining bee species, including Clarke's mining bee, which specialises on it.
• Lamb's ear: its downy leaves are what the wool carder bee scrapes to build its nest, not just a nectar source.
• Ivy: flowers late, in autumn, when little else is in bloom, a genuine late-season nectar source for whichever solitary bees are still flying. The specialist ivy bee that depends on it entirely is currently found mainly in southern England and Wales, not yet established in Scotland.

The key window for a garden to be in flower for pollinators runs from March to October.

Why it matters

Over 250 British species between them means solitary bees are pollinating alongside bumblebees in most gardens, often unnoticed since none of them form the kind of visible colony a bumblebee nest does. Bumblebees nest in existing cavities, tunnels and long grass and can't be given a purpose-built home; several solitary bee groups, leafcutter and mason bees especially, take readily to one, giving a gardener a genuine, active way to help beyond planting. The red mason bee is efficient enough at pollinating fruit trees that it's sometimes deliberately introduced to orchards further south, though it's genuinely uncommon in Scotland itself.

Frequently asked questions

Sources