[3] When a conidium or blastospore of Isaria fumosorosea lands on a suitable host, it produces enzymes to penetrate the insect's cuticle.

[5] This fungus has a wide host range that includes insects in over twenty five different families and many species of mite.

Agricultural pest insects which are susceptible to infection include the diamondback moth (Plutella xyllostella), the Russian wheat aphid (Diuraphis noxia) and the silverleaf whitefly (Bemisia argentifolii).

[6] A comparison made between several entomopathogenic hyphomycetes showed that Isaria fumosorosea (as Paecilomyces fumosoroseus) provided more effective control of the cabbage-heart caterpillar, Crocidolomia binotalis, than did either Beauveria bassiana or Metarhizium anisopliae.

It has not been found to be toxic to rats in laboratory experiments and is not considered to be harmful to birds, honey bees,[9] bumblebees or a wide range of non-target arthropods.