Grassland management had a negative effect on stem-borer colonization success and spatial niche differentiation. Reducing management over a 1-season period did not enhance abundances. Two out of three species responded positively only to an abandoning treatment lasting ¡Ý2-seasons, which was also reflected by the decreasing spatial overlap in this treatment. Even though grass shoots in unmanaged areas were on average 14.9 cm taller than in managed areas, stem-borer abundances did not differ between the latter treatments. Hence, preserving essential larval development and hibernation habitats in future rotational set-aside schemes requires a management exclusion period of at least two growing seasons. From these grassy strips, e.g. located at meadow edges, highly specialized stem-borers can re-colonize sward islets on surrounding intensively managed grasslands, despite of ever changing land-use practices and environmental conditions.