The exotic insect, emerald ash borer Agrilus planipennis, is established in Michigan and in some surrounding states. At high population densities, all green, black and white ash trees are apparently susceptible to attack and can be expected to die. Long-term prospects for management of the beetle from Asia include biological control to reduce population densities of the insect, and resistance or tolerance of ash trees to reduced populations of the pest. In the short term, reduction of pest populations in local areas is achievable by removal of its breeding substrate. Emerald ash borer larvae develop in the phloem of ash trees in stems and branches above approximately 2.5 cm diameter. While the amount of phloem needed to complete development is not yet known, we can estimate the amount of phloem available to the insect in a stand of ash. We are therefore developing models of the amount of ash tree removal necessary to reduce the breeding substrate by a target percentage. This model will become available to land managers aiming to reduce the potential for damage by emerald ash borer.