In 2019 Sander Bot and Frank van de Meutter published “Veldgids Zweefvliegen” [Field Guide to Hoverflies of the Netherlands and Belgium] in Dutch. The publisher Bloomsbury requested that they produce an English version with an expanded geographical range – including Great Britain, Ireland, Denmark, Luxembourg and parts of western Germany and northern France. Sander and Frank approached Stuart Ball to help with the distribution maps and phenology plots. For this purpose, we combined data from the recording schemes in Belgium, Great Britain, Ireland and the Netherlands. Unfortunately, similar collations of detailed hoverfly records were not available for Denmark, Luxembourg and the regions of France and Germany to be covered. Up to date lists of the species present in these areas were assembled by Frank. In this talk I will describe some of the challenges arising from combining data collected in different formats, using different spatial reference systems and conforming to different checklists. I will illustrate the maps that were eventually produced, combining a more detailed analysis of the distribution and abundance of species from the areas covered by recording schemes with the presence/absence data for the remainder. I will also illustrate the phenology plots which contrast the flight period in Belgium and the Netherlands with that in the south-eastern and north-western British Isles.