The vector potential of the rabbit flea (Cediopsylla simplex) and a mosquito (Aedes triseriatus) was investigated for Herpesvirus sylvilagus transmission among cottontail rabbits (Sylvilagus floridanus). Twelve groups of 12–50 fleas were fed on three viremic cottontails for 2–21 days before transfer to 12 susceptible rabbits. Standard interrupted feeding trials employed five groups of 6–12 mosquitoes, two viremic donor cottontails and five healthy recipients. No evidence of virus was detected from recipients' blood nor did they develop specific antibody. Virus acquisition and persistence in the insects was evaluated by attempting to recover the virus from 19 pools of mosquitoes engorged on viremic blood and 36 pools of engorged fleas or those living on viremic hosts for 1–21 days. Results were negative.