The holly leaf miner is an Holarctic species. It is widespread throughout Great Britain and Ireland and has been recorded in over 50 counties.
View the National Biodiversity Network (NBN) grid map for Phytomyza ilicis.
View the NBN grid map for Ilex aquifolium.
It is also common and widespread in Europe, including:
It has been introduced into western Canada and the north-west USA.
The fly is common in woodlands, hedgerows, parks and gardens in Europe and North America
The adult fly is not easily observed because of its small size. The characteristic mines however, are very obvious and can be sought wherever holly - which is mainly cultivated as an ornamental tree - is found.