Abstract
A broad understanding of fungal parasitism of insects has now arisen thanks to the growing amount of study that the subject has received. In some areas this understanding is fairly deep, but for too many host-parasite combinations, and indeed fungus parasites considered in isolation, it is still superficial. Numerous problems remain to be elucidated by mycologists, entomologists, and insect pathologists, employing modern and penetrating research techniques. There is still great ignorance of the basis of (a) the capacity of some fungi, yet not others, to attack insects; (b) the host specificity shown by so many fungus parasites; (c) the different degrees of virulence of strains of the same species; and (d) the capacity for changes in virulence of particular strains. Unitl these and other problems have been solved the appliaction of fungi in biological control of insect pests must continue to be largely empirical.