No biologist who has penetrated and explored a truly virgin forest in the tropics has ever reported the occurrence of insect epidemics or has seen evidence of extensive defoliation and borer damage. In tropical evergreen forests with their numerous species of trees and still more numerous hordes of insect species, the absence of epidemics is not surprising.

Mixed stands are much safer from insect injury than are pure stands. In fact, we may safely say that the greater the diversification of tree species, the less frequent will be insect outbreaks. This is an illustration of the general principle that other things being equal, the degree of environmental stability is in direct proportion to the number of species living together in an environment.

It can be generally stated that extensive outbreaks of defoliating insects are uncommon in the high forests of Ghana. This is true because the forests have a high degree of species diversity and most insects have a narrow host range. …[…]