The aim of this work is to study the toxicity of a commercialized strain of Bacillus thuriengiensis alone and with the addition of 5% dextrin with a growth regulator Diflubenzuron towards the L3 stage of a date palm pest Or the date worm Ectomyelois ceratoniae. Results showed that the efficacy of the bacterial strain added to 5% Dextrin recorded the highest mortality rate at 75.74%, compared with the bacterial strain alone 67.04%, while Diflubenzeron appears to be less effective, recording a low mortality rate of only 44.82%.