Status of defoliator populations and trends can be determined through predictive and population sampling methods.
Stands appear brownish or scorched immediately after a season of defoliation.
Initially, defoliation is concentrated at the tips of branches on current foliage, or at the tops of trees. Primary host trees suffer the most defoliation with other tree species being defoliated to a lesser extent when they are intermingled with the preferred host. Canopy and understorey trees will have chewed foliage and take on a brownish tinge. Proper identification of the defoliator species is critical. Other damaging agents can cause discoloration and needle loss which may cause confusion when doing aerial surveys.