The effects of five temperature regimes and five artificial culture media on germination,rnradial growth and sporulation of four Beauveria and two Metarhizium isolates obtainedrnfrom various ecological zones of Ethiopia were investigated in vitro. The susceptibility ofrnadult Aphis gossypii to four concentration levels (105, 106, 107 and 108 conidia ml-1) ofrnthese fungal isolates was evaluated with direct spraying bioassay at 20, 25 and 300crnunder laboratory conditions. All experiments were replicated three times usingrncompletely randomized design. Germination, radial growth and sporulation of all fungalrnisolates were slower at 150c than 20, 25 and 300c. At 350c none of the Beauveria isolatesrnwere able to germinate after 24 hour post inoculation. A suitable temperature forrngermination and radial growth was ranged from 20 - 300c for all fungal isolates. Thernmaximum rate of growth per day was obtained at 300c followed by 250c. As regards tornartificial culture media, all fungal isolates showed maximum radial growth on OMA.rnIsolate MM and ICIPE 30 revealed the highest sporulation and fastest germinationrnpercentage 60% and 77% after 8 hour on OMA, respectively. The Beauveria isolate,rnDLCO 105 showed the highest sporulation on SDA and PDA. The maximum rate ofrngrowth per day was obtained on OMA with all the fungal isolates. The result of thernbioassay showed that at 25 and 300c, all tested isolates with 1 x 108 conidia ml-1 werernvirulent (73.33 â€“ 93.33% mortality and LT50 ranged from 3.82 - 4.96 days) and (82.22 -rn100% mortality and LT50 ranged from 3.22- 4.01 days) to Aphis gossypii, respectively.rnThe Beauveria isolate DLCO 87 had the lowest LC50 value at 20 and 300c and DLCO 41rnat 250c.The results of the present study suggest that the potential use of nativernentomopathogenic fungi as an alternative method to chemical pesticides may holdrnpromise for the management of Aphis gossypii in Ethiopia.