Technical Abstract: This chapter provides basic information to aid the identification of fungal pathogens known to affect chrysomelid hosts and discusses the practical use of fungi for the biological control of chrysomelid pests as well as means to protect chrysomelids from fungal attack (especially in laboratory cultures of these insects). The discussions of individual fungal species -- -BEAUVERIA BASSIANA, METARHIZIUM ANISOPLIAE, PAECIOMYCES species, VERTICILLIUM LECANII, and a few species from the Entomophthorales -- include lists and illustrations of major diagnostic characters and are supplemented by a key for the idewntification of these fungi, a listing of chrysomelid species and their associated fungal pathogens as well as an updated list of ectoparasitic ascomycetes of the Laboulbeniales that affect the Chrysomelidae. The brief discussion of the practical use of fungi to control chrysomelids that are agricultural pesats focuses on the use of BEAUVERIA BASSIANA to control Colorado potato beetle, LEPTINOTARSA DECEMLINEATA.