Deformed wing virus (DWV) can cause wing deformity and premature death in adult honey bees, though like many other bee viruses, DWV generally persists as a latent infection with no apparent symptoms. Using RT-PCR and Southern hybridization, we detected DWV in all life stages of honey bees including adults, with and without deformed wings. We also found DWV in the parasitic mite, Varroa destructor, suggesting this mite may be involved in the transmission of DWV. However, the detection of virus in life stages not normally associated with mite parasitism, i.e. eggs and larvae, suggests other modes of transmission. Levels of DWV in different life stages of bees were investigated by TaqMan real time quantitative RT-PCR. Amounts of virus varied significantly in these different stages, with the highest levels occurring in pupae and in adult worker bees with deformed wings. The quantification of virus load in the living bees provides essential information on the virus pathogenesis and epidemiology. Variability in virus titer may reflect the different abilities of bees to resist DWV infection and replication.