Mason bees vs leafcutter bees
The two solitary bees most likely to occupy a bee hotel, and the easiest pair to tell apart once you know that one carries mud and the other carries leaves.
Which to choose
Not a choice — provide for both. Tubes of 6 to 10 mm facing south-east in full morning sun serve mason bees in spring and leafcutters in summer. Add bare damp clay soil for the masons and leave the rose leaves alone for the leafcutters, and clean or replace the tubes every year or two, which is the step that decides whether a bee hotel helps or eventually harms.
Why these get compared
They are close relatives using the same nest sites in the same garden, and most people who put up a bee hotel end up with both without realising they are different animals.
Where they differ
| Axis | Mason bees | Leafcutter bees | Why it matters |
|---|---|---|---|
| Nest material | Mud, carried in the mandibles and used as partitions between cells | Neat oval pieces cut from leaves and petals, glued into a thimble | The single reliable field character. A bee flying into a tube carrying a green disc is a leafcutter; one carrying a pellet of wet clay is a mason. |
| When | March to June, and gone by midsummer | June to August, appearing as the mason bees finish | Timing alone separates them in most gardens, and it means one bee hotel serves both across the season rather than either one alone. |
| What they pollinate | Spring blossom — apple, pear, cherry, plum, hawthorn, blackthorn | Summer flowers, and commercially alfalfa and legume seed crops | Mason bees are among the most effective fruit pollinators known, several times more so per individual than honey bees. Leafcutters underpin the North American alfalfa seed industry for a completely different reason — they tolerate being struck by the flower's tripping mechanism, which honey bees learn to avoid. |
| Pollen carrying | Dry, on the underside of the abdomen | Dry, on the underside of the abdomen | The same, and the same consequence: loose dry pollen sheds readily onto the next flower, which is why both outperform honey bees per visit. A honey bee's wetted leg pellet stays put. |
| What the gardener notices | Mud plugs sealing tubes, and a need for bare damp clay within about fifty metres | Neat semicircular notches cut from rose and lilac leaves | Both prompt complaints and neither warrants one. The leaf cutting does no harm to the plant, and the mud requirement is the constraint most bee hotels quietly fail on. |
Where the difference is overstated
Their sting. Both are described as stingless in a great deal of garden writing, which is not quite right — the females have stings and are functionally incapable of using them on a person. The practical answer is the same; the accurate statement is different.
Sources
- Field Guide to the Bees of Great Britain and Ireland — Bloomsbury (2015) · Field guide
- Assessment Report on Pollinators, Pollination and Food Production — Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) (2016) · Systematic review Link
How sources are selected and weighted is set out in the sources and evidence policy.