Abstract
The within crown distribution of three species of Pleroneura and their food source (active buds) was determined on white fir trees 5–30 ft tall. Over 90% of all active buds and 94% of all infested buds occur in the outer half of the crown. Over 50% of the total active and infested buds occur in the middle third of the crown. Percentage infestation within the crown increases from bottom to top. Percentage infestation per tree decreases as tree size increases.