Filth flies have been implicated in the dispersal of human disease pathogens; however, the epidemiological parameters of the transmission of human pathogens from flies to plants are largely undescribed. The capacity of the black blow fly, Phormia regina Meigen, to acquire and subsequently deposit bacteria onto baby lettuce leaves was compared with that of the house fly, Musca domestica (L.). Adult P. regina and M. domestica were exposed to green fluorescent protein-tagged Escherichia coli O157:H7- or Salmonella enterica-inoculated manure and then allowed access to the lettuce plants. Bacteria on the plants and flies were assessed by plating and polymerase chain reaction. Although blow flies acquired significantly more E. coli O157:H7 than house flies, there was no significant difference between the deposition of bacteria on lettuce by the two fly species. In contrast, there was no significant difference in the acquisition of S. enterica by the two fly species. However, blow flies deposited more S. enterica onto lettuce than house flies. To more accurately assess transmission parameters, flies were given timed exposure and inoculation periods of 10 and 30 s. Blow flies acquired more E. coli O157:H7 than S. enterica in the both time periods. Flies exposed to manure for 30 s were then tested for deposition by forcing the flies to walk on lettuce leaves. Blow flies deposited comparable amounts of E. coli O157:H7 and S. enterica. Although house flies have historically been implicated in the transmission of human pathogens to food, the data presented suggest that blow flies are more efficient vectors of E. coli O157:H7 and S. enterica to leafy greens than house flies.