Influence of the holly leaf miner,Phytomyza ilicis (Diptera Agromyzidae), on leaf abscission

Holly trees were sampled at two heights for 11 annual generations of Phytomyza ilicis Curtis. The number of mines per 1000 leaves, mine intensity, was consistently more at the lower height. Mine-induced leaf abscission led to a reduction in mine intensity from 1- to 2-year-old leaves. Abscission was shown to have been greater in samples taken from higher in the tree. There was a suggestion of a density-dependent effect on the probability of mine-induced abscission.