Two new species of the ascosporic yeast genus Metschnikowia were isolated from nectaries and associated muscoid flies of flowers from the common milkweed (Asclepias syriaca) in North America, and are described as Metschnikowia vanudenii [type strain=PYCC 4650(T)=CBS 9134(T)=NRRL Y-27243(T)=UWO(PS) 86A4.1(T)] and Metschnikowia lachancei [type strain=PYCC 4605(T)=CBS 9131(T)=NRRL Y-27242(T)=UWO(PS) 7ASB2.3(T)]. As with the previously described Metschnikowia gruessii, M. vanudenii has vegetative cells with an 'aeroplane' or cross-like configuration, produces ovoid chlamydospores and forms ellipsoidopedunculate asci with two acicular ascospores. Metschnikowia lachancei is distinguished from other Metschnikowia species by formation of club-shaped asci with 1-2 thick clavate ascospores. The phylogenetic positions of the proposed new species within Metschnikowia were determined from sequence analysis of the D1/D2 domain of 26S rDNA. The new species show low nuclear DNA relatedness with neighbouring taxa.