Cassida vittata Vill.(Coleoptera :Chrysomelidae) is  avery important insect pest to sugar beet crop. Its larvae and adults feed upon sugar beet leaves causing significant defoliation, consequently reduce root weight and sugar percent (%) to this crop. Entomopathogenic microorganisms, mainly entomopathogenic bacteria, is a vital factor of the natural mortality against insects. Research on microbial pathogens of insects is increasing to find out environmental friendly alternatives to hazardous chemicalinsecticides. This investigation was done at the Experimental Farm of Sakha, Agricultural Research Station, Kafr Elsheikh Governorate, Egypt during 2018 and 2019 seasons. Obtained results showed that 11(29.72%) C. vittata larvaeout of 37 individuals died naturally with Bacillus aryabhattai. Six(29.72%) C. vittata adults out of 25 individuals died naturally due to exposure to 10⁸ cfu/ml suspension, which used for laboratory and field tests. In a laboratory test, the mortalities of larvae were 20.00, 30.00 and 45.00% after 3, 7 and 10 days post-treatment, respectively. Whereas, the mortalities of adults were 10.00, 25.00 and 40.00% after 3, 7 and 10 days post-treatment, respectively. Also, in a field test, the reduction of larvae were 12.86, 29.79 and 43.99% for 3, 7 and 10 days after treatment, respectively. Reduction of adults were 14.06, 27.05 and 39.84% for 3, 7 and 10 days after treatment, respectively. This strain was identified by GATC (biotech sequence company, Germany), for the first time in Egypt. These results conclude that this strain is an effective biocontrol agent against C. vittata larvae and adults in sugar beet fields.