Trialeurodes vaporariorum is an important greenhouse pest worldwide. We compared the efficacy of a new strain of Beauveria bassiana (ARP14) with a commercialized one (GHA) against 2nd instar and 4th instar of T. vaporarioum. Those nymphs were exposed to the fungus in a concentration of 1×108 conidia/mL by leaf dipping method. There was no difference in mycosis rates at any observation time between the two strains in both 2nd (100.0%) and 4th instar (100.0%). Lethal median time (LT50) wasn't different between the two strains in both 2nd and 4th instar. In conclusion, the new B. bassiana strain (ARP14) would be a good candidate of mycoinsecticide for whitefly management.