Abstract: The conidial powder of Beauveria bassiana SG8702 produced using a diphasic fermentation technology was formulated into emulsifiable suspention I (ES-I, >10¹⁰ conidia穖l^-1) and ES-II, which resulted from adding1% (W/V) of imidacloprid 10% WP to the ES-I. Three dilutions (10⁷, 10⁶, and 10⁵ conidia穖l^-1 of each were sprayed onto cabbage plants for control of the green peach aphid Myzus persicae population in field plots in Kunming, Yunnan during July 2001. Each dilution and a water spray as control were replicated three times. During a 28 d period of sampling at 3 or 4 d intervals, spray of the ES-IIat 10⁷ conidia穖l^-1 controlled the increase of the aphid population by >90% consistently from day 7 after spray. The efficacy for the ES-Iat the same concentration reached 85% on day 7 after spray, exceeded 70% in the following two weeks, but declined to 64.4% on day 24 and 52.6% on day 28. At the lower concentrations sprayed, both suspensions significantly suppressed the increase of M. persicae population, but the ES-II resulted in higher efficacy than the ES-I. Local summer weather with mild temperature and frequent rainy days was favorable to the use of the formulations for aphid control.