Nomad bees

How to recognise it

Small to medium, sparsely haired and shining, marked in combinations of red, yellow and black that convincingly resemble small wasps. No pollen-carrying structures of any kind, which is the defining feature.

• Wasp-like: shining, near-hairless, boldly marked.
• No pollen brushes anywhere — the diagnostic character for the whole cuckoo strategy.
• Flying low and slowly over bare ground where mining bees nest, dropping into holes and coming out again.
• Never carrying a pollen load, because it gathers none.

Body length 4–15 mm (typically 9 mm).

Biology

Social organisation

Cleptoparasitic — lays in other bees' nests

Builds no nest and gathers no pollen for her own young, laying instead in another bee's provisioned cell. Sometimes called cuckoo bees.

Nesting

Builds no nest

Builds nothing. The female inserts an egg into the wall of a provisioned host cell, frequently before the host has finished sealing it, so that it hatches within the closed cell. The first-instar larva has enlarged sickle-shaped mandibles used to kill the host egg or larva.

Carries pollen

Carries no pollen for young

On the wing

March to September

Lifecycle

1. 1Emergence timed to the hostEach species emerges when its particular host does, which is why the genus as a whole spans the season while any one species flies for a few weeks.
2. 2SearchingThe female patrols host aggregations for hours, testing burrows. This slow searching flight is the characteristic behaviour.
3. 3Egg insertion and host eliminationShe lays into the cell wall; the larva hatches, kills the host offspring and consumes the provision.

Where it lives and what it does

Habitat

Wherever the hosts nest — sandy banks, lawns, footpaths, brownfield land, heathland and coastal cliffs.

Distribution

Worldwide except Australia, following the distribution of Andrena and related genera.

Behaviour

Unhurried and searching. Because Nomada need no pollen, they spend far less time at flowers than their hosts and are correspondingly harder to notice — and because many are host-specific, a Nomada record frequently establishes the presence of a host species nobody has seen.

Pollination role

Negligible as pollinators. Their value is as indicators: an obligate parasite requires a host population large enough to sustain it, so their presence is evidence of habitat quality rather than a problem to solve.

Incidental only. This is the bee group whose value is not pollination.

What it forages on

Visits flowers for nectar only, and is unfussy about which. The specialism is the host, not the forage.

Honey

Produces no honey

None. No nest, no colony, no stores of any kind.

Relationship with people

How people interact with it

Routinely killed as wasps and otherwise unknown. Because many species are host-specific and scarce, they are disproportionately represented on conservation priority lists.

Conservation

Cuckoo bees decline faster than their hosts and recover more slowly, because they need the host abundant rather than merely present. Several Nomada are among the most threatened bees in Europe, and a site losing its Nomada has usually already lost host density.