Infective conidia from entomopathogenic fungi are widely used to control insect pests. Many entomopathogenic fungi also produce yeast-like cells called blastospores under specific liquid culture conditions that can directly infect insects. However, little is known about the biological and genetic factors that allow blastospores to infect insects and make them potentially effective for biological control in the field. Here, we show that while the generalistMetarhizium anisopliaeproduces a higher number of and smaller blastospores, the Lepidoptera specialistM. rileyiproduces fewer propagules with a higher cell volume under high-osmolarity conditions. We compared the virulence of blastospores and conidia of these twoMetarhiziumspecies towards the economically important caterpillar pestSpodoptera frugiperda. Conidia and blastospores fromM. anisopliaewere equally infectious, but acted slower, and killed fewer insects thanM. rileyiconidia and blastospores did, whereM. rielyiconidia had the highest virulence. Using comparative transcriptomics during propagule penetration of insect cuticles, we show thatM. rileyiblastospores express more virulence-related genes towardsS. frugiperdathan doM. anisopliaeblastospores. In contrast, conidia of both fungi express more virulence-related oxidative stress factors than blastospores. Our results highlight that blastospores use a different virulence mechanism than conidia use, which may be explored in new biological control strategies.