What is "holly leaf miner"

Phytomyza ilicis, the holly leaf miner, is a fly whose larvae burrow into leaves of the holly tree ( Ilex aquifolium) leaving characteristic pale trails or leaf mines. The holly leaf miner has frequently been used in ecological studies as a system to study food webs since examination of the leaves can reveal whether the leaf miner has successfully emerged, been killed by a parasitic wasp, or been predated by blue tits.