The Lady’s slipper orchid Cypripedium calceolus L. is considered one of the most beautiful orchids of Europe.
Consequently, the species has suffered from over-collecting and is now critically endangered in many countries. Although
pollination success is suspected to influence the long-term survival of Cypripedium calceolus, relatively little is known
about the identity of its pollinators in mainland Sweden � a region that comprises the largest European populations. In
order to identify which species pollinate eight representative populations in mainland Sweden, we observed and sampled
visitors to flowers using a standardized protocol. Specimens were identified and any pollen smear found on their body was
examined for the presence of Cypripedium pollen. Nine species were recognized as effective pollen vectors (Andrena
cineraria, A. carantonica, A. haemorrohoa, A. helvola, A. nigroaenea, A. praecox, Colletes cunicularius, Lasioglossum fratellum
and L. fulvicorne), four of them for the first time in Scandinavia. This is the first time that a species of Colletes is reported
to carry pollen of Cypripedium in this region. All but one specimens were females. Our results suggest a taxonomically
heterogeneous pollinator fauna for Cypripedium calceolus and are discussed in light of the management of this species.