Fleas have caused health and sanitation problems for centuries. Most rodents are hosts to fleas. Baker Crop Protection Chemicals (BCPC) recently entered the rodenticide market (via SLN) with an efficacious fumigant for single burrow rodents, MAGNACIDE® H Herbicide/Rodenticide (a.i. acrolein). Noting that most burrowing rodents are flea infested, BCPC undertook an experiment to determine if fleas also succumb to acrolein under simulated field treatment scenarios. Results of the study under laboratory conditions demonstrated that fleas do succumb to acrolein treatments as well as the specific rodents targeted for treatment. This study also established rodent death rates from exposure to acrolein in a simulated closed system at 4 to 6 minutes, at a treatment rate of 20 milliliters