This dataset contains samples and occurrences of insects and flowers collected for the 1 km square survey of the UK Pollinator Monitoring Scheme (PoMS). It covers the years 2017 to 2020 (note that 2017 was a pilot year and has less data than subsequent years). This survey uses pan-traps positioned on transects within a randomly allocated set of 1 km squares in England, Scotland and Wales. The sample data contains information on the location of the traps, various environmental variables, and the total number of insect specimens collected. The occurrence data for insects contains records of all hoverflies and bees from the traps, identified (wherever possible) to species level. The occurrence data for flowers contains records of all forbs that are in flower within 2 metres of each pan-tap station. (In addition, Flower-Insect Timed Counts are carried out in the same 1 km squares, see separate dataset for these data.) The UK Pollinator Monitoring Scheme is a partnership between the UK Centre for Ecology & Hydrology, Bumblebee Conservation Trust, Butterfly Conservation, British Trust for Ornithology, Hymettus, Natural History Museum, University of Reading and University of Leeds, working with the Bees, Wasps and Ants Recording Society, wider stakeholders and volunteer networks. PoMS in 2017-2020 has been jointly funded by Defra, the Welsh and Scottish Governments, JNCC and project partners.