The alien black-and-yellow mud dauber, Sceliphron caementarium (Drury, 1773) (Hymenoptera, Sphecidae), continues its spread: new citizen-science records from Eastern Europe and the Balkans.
The Nearctic Sceliphron caementarium (Drury, 1773) is widely distributed in the Western Palearctic and is spreading to new territories. Despite the large quantities of data on citizen-science platforms, these records have been mostly overlooked. In this publication, the first records of S. caementarium from six Eastern European and Balkan countries (Albania, Greece, Montenegro, Poland, Serbia, and Slovakia) are presented. Data derived from online citizen-science observations and museum specimens supplement our knowledge of this species' range. The distribution of this species in Europe and possible ecological implications are discussed.