Erin is investigating the role of parasite preference for certain hosts during the infection process. Heterogeneity in infection among hosts is often attributed to differential exposure and/or susceptibility to infection within the host population. However, a third and potentially important factor remains relatively unexplored. In many parasites, the infective stages are capable of actively seeking out a susceptible host to infect. There is no reason to expect this process to be solely random. Indeed, parasites may be preferentially infecting certain hosts in order to maximize transmission, probability of establishment, and/or subsequent replication success. Erin is experimentally testing host preferences by a parasitic mite that attacks fruit flies (Drosophila hydei). She has found that mites preferentially attacked females hosts when given a choice between male and female flies. Interestingly, the outcome was modulated by mite condition: when mites were starved for 24 hrs males were more likely to be parasitised than female flies. She is currently investigating the underlying mechanism of the mite’s sex-biased infection.