19/07/2023
A medium-sized solitary bee (9-12mm) which gets its name from how the females constructs their nests. They cut out perfect discs from the leaves of plants, including roses and lilac – making them look as if they’ve been attacked by a hole-punch – to create cells for their young to develop in.
They emerge in June and fly until September, peaking this month. Common in England and Wales, Megachile centuncularis can be spotted in parks and gardens often feeding on thistle-like flowers.
They are a brownish grey and a little smaller than a honeybee, but the easiest way to identify them is to observe how they collect pollen. On the underside of the female bee’s abdomen are orange coloured pollen brushes. As leafcutter bees have a habit of lifting up their abdomen into the air while feeding on flowers, this orange underside is clearly visible.
Another way to identify them is if you see a female flying home clasping a piece of leaf, like a witch riding a broomstick. As well as constructing cells with the leaf discs she also uses leaves to plug the holes of the cavity where she is nesting. The cavity could be in dead wood or bramble stems, or in manmade structures like solitary bee hotels, where she can be found next door to Red mason bees who plugged their entrance with mud back in April and May.
There are 7 species of leafcutter bee in the UK. Worldwide there are 1,500 species including the world’s largest bee, the Indonesian Megachile pluto, or Wallace’s giant bee, measuring 40mm long with a huge 63mm wingspan and jaws like a stag beetle.
Helping leafcutter bees
1. Grow food and nesting material
Let thistles flourish in a wild part of your garden along with brambles, and grow ornamental thistles, like Knapweed, as well as yellow-flowered legume Bird’s-foot Trefoil. For nesting material, grow rose bushes (single-headed roses will feed bees too), willowherbs, lilac, and honeysuckles. The bees also collect leaves from horse chestnuts and birch trees.
2. Leave dead wood and bramble stems
They nest in pre-existing cavities.
3. Install a bee hotel or a bee observation box
Leafcutter bees will often nest next door to Red mason bees in bee hotels or bee observation boxes installed in early spring, at least a metre off the ground in a warm, sunny spot. It’s not too late to put one up now and see if any get plugged with leaves.
For other bees to see this month, how to tell them apart, and how to help them, sign up to Alison’s free Buzz newsletter
Words: Alison Benjamin, Urban Bees
