We constructed several multilocus DNA sequence datasets to assess the phylogenetic diversity of insecticolous fusaria, especially focusing on those housed in the Agricultural Research Service Collection of Entomopathogenic Fungi (ARSEF), and to facilitate molecular identifications of unknowns via the FUSARIUM-ID and Fusarium MLST online databases and analysis packages. Analyses of a 190-taxon two-locus dataset, which included 159 isolates from insects, indicated that: 1) insect-associated fusaria were nested within 10 species complexes spanning the phylogenetic breadth of Fusarium, 2) novel, putatively unnamed insecticolous species were nested within 8/10 species complexes, and 3) Latin binomials could be applied with confidence to only 18/58 phylogenetically distinct fusaria associated with pest insects. Phylogenetic analyses of an 82-taxon three-locus dataset nearly fully resolved evolutionary relationships among the 10 clades containing insecticolous fusaria. Multilocus typing of isolates within four species complexes identified surprisingly high genetic diversity in that 63/65 of the fusaria typed represented newly discovered haplotypes. The DNA sequence data, together with corrected ABI sequence chromatograms and alignments, have been uploaded to the following web-accessible sites dedicated to identifying fusaria: FUSARIUM-ID (http://isolate.fusariumdb.org) at The Pennsylvania State University's Department of Plant Pathology and Fusarium MLST (http://www.cbs.knaw.nl/fusarium) at the Centraalbureau voor Schimmelcultures (CBS-KNAW) Fungal Biodiversity Center.