Heavy defoliation of black cherry by Hydria prunivorata significantly reduced growth at breast height the following year. Growth in the crown of defoliated cherries approximated predefoliation levels. Red maple in defoliated stands increased significantly in growth at breast height during the years cherry growth was reduced. Black cherry trees with above average growth prior to defoliation showed the greatest absolute reduction in growth following defoliation. Red maples with average, slightly above, or slightly below average growth showed the greatest growth increases following cherry defoliation. Total growth reduction in the defoliated black cherries under observation was greater than the total increases in growth of an equal number of red maples. The value of black cherry wood lost due to reduced growth was greater than the cost of an areial insecticide application during each year of the defoliation.