The sugar beet flea beetle (Chaetocnema tibialis Illiger 1807) does inflicts damagethe big damage to young sugar beet crops. The suppression of sugar beet flea beetle has been achieved by seed of seeds treatedsugar beet seeds treatment with systemic insecticides from the group of neonicotinoids. In 2018. their use has been prohibited for this purpose whichThe ban on the use of neonicotinoid that occurred in 2018 is likely to lead to major problems with the flea beetles. In addition, there was a suspicion that populations of sugar beet flea beetle started to developed resistance to insecticides. Therefore, it is extremely important to determine the efficacy of other active substances that could serve as an adequate substitution for neonicotinoids. All this has led to the need to find new active substances of a favorable ecotoxicological profile that could be used to suppress flea beetle. The aim of the study was to evaluate the efficacy of imidacloprid and thiamethoxeams applied foliar on flea beetles and to investigate the effectiveness of botanical insecticides and organic nitrogen fertilizers (Boundary SW). During the experiment, the problemsre were appeared problems with the flea beetle manipulation of sugar beet flea beetle occurred in laboratory conditions. For this reason, further research was carried out on the cabbage flea beetle population of cabbage flea beetle. Cabbage flea beetles as well as sugar beet flea beetles appear in large populations on young cabbage plants and it wasis also necessary to check the effectiveness of current and alternative insecticides. The gathering collection of sugar beet flea beetles with manual aspirator wereas carried outcollected on two sites (Lukač and Tovarnik), and collection of cabbage flea beetles wereas has been carried out at the location of Dugo Selo Lukačko. The experimental plants were grown from untreated seeds. The experiments were performed by soaking the leaves in the spray solution (IRAC No. 7). The test experiment was observedmonitored during for 24, 48 and 72 hours, and the number of dead flea beetles caused out from insecticides and control variants was used to calculate efficacy by the Schneider - Orelli formulaon insect killer and control variants was used to calculate efficacy by the Schneider - Orelli formula. The results showed that during the experiment with flea beetles one should take carespecial attention should be focused of the experimentalon the methodology itself. The recommended implementation procedure by using petri dishes makes it difficult to manipulate with flea beetles and significantly affects the results themselves. Results shown that Ccabbage flea beetles did not develop resistance to neonicotinoids, high population number in fields conditions and ineffectiveness of currentpoor insecticides activity are likely probably the to result from of poor and bbadly and un timelyd application. Neonicotinoids (thiamethoxam and imidacloprid) work wellshown good efficacy on cabbage flea beetles and can be used by treating seedlingsseedling treatment in protected areasgreenhouses. The botanical insecticide azidirachtin as well as the nitrogen fertilizer have shown sufficient satisfactory efficacy in suppressing the flea beetles and can be recommended as adequate substitution an alternative in the case of further prohibition of insecticides so far used.