his dataset consists of behaviour and distribution data of Lepidoptera from mown chalk grassland boundaries at the Stonehenge World Heritage Site in Wiltshire, UK, between July and August 2012. The landscape consisted of a mosaic of chalk grassland fragments on ancient burial mounds (barrows) and slopes, grassland re-creation fields of different ages since sowing, semi-improved pasture, arable farmland and woodland. In one of the grassland re-creation fields, two large areas were mown and eight 20 m long survey boundaries were set up. Four of these were set up on the edge of one of two mown areas and four were set up in areas of continuous un-mown grass which had dummy 'boundaries' parallel to the mown boundaries. The survey was conducted from the survey boundary and the flight path of individual Lepidoptera was tracked in the area 10 m either side of the survey boundary. Each individual Lepidoptera flight path was surveyed for three minutes. Each boundary was surveyed for a total of 20 minutes on three occasions over a five week period. The sequence of boundaries surveyed was chosen randomly and equal survey effort was allocated to visually searching both sides of the boundary. The order and time of day for surveying each survey area was random so to spread surveys throughout the survey period and throughout the day. Measures of vegetation characteristics and nectar flower availability were recorded for survey areas. Recorded vegetation characteristics included vegetation height and density. Nectar flower availability was measured as the number of flowering units of nectar flowers and numbers of those in the Asteraceae, Fabaceae and Dipsacaceae families. The data were collected as part of a PhD project funded by the Natural Environment Research Council and the National Trust. Full details about this dataset can be found at https://doi.org/10.5285/e3598268-22d7-4913-a736-890728ea858b