The effect of damage by the heliozelid leafminer,Coptodisca negligensBraun, on abscission of cranberry,Vaccinium macrocarponAiton, leaves was studied in Connecticut during 1986. The abscission of second-year leaves was significantly greater and earlier on wild and potted vines with leafminer injury than on those without injury. The mean week of abscission was significantly earlier (about 1 wk) for leaves with two miners than for those with one miner. Wild plants in a bog dropped most of their mined leaves during June when fourth instars ofC. negligenswere completing their development. In the laboratory, 90% of 20 fourth instars in detached leaves survived to construct oval leaf cases for pupation.