Sugar beet is an extremely important industrial plant in Croatia and Austria. As the only raw material for the production of crystallized sugar in Europe, preserving its production is of great importance. In the last few years, there has been a trend of reducing sugar beet production due to high requirements in the form of agrotechnical measures, the need for large investments and excellent knowledge about the production itself, with additional aggravated conditions as a result of climate change. Sugar beet has a long growing season during which a large number of pests attack. Flea beetles are among the important and regular pests of sugar beet that cause damage in the development stage of the cotyledons and the first true leaves. There are two species of the genus Chaetocnema that cause damage to fields in Croatia and Austria, namely Chaetocnema tibialis Illiger and Chaetocnema concinna Marsham. The literature states that C. tibialis dominates in both countries, but the exact abundance ratios and more detailed explanations of the factors influencing the population dynamics have not been sufficiently investigated. The aim of this work was to determine which species dominates the production areas, as well as to collect more data on the distribution of these species in Austria and Croatia. In April and May 2022, fleas in Austria were collected using the yellow container method on several occasions, while fleas in Croatia were collected using the aspirator method in August of the same year. Using identification keys based on several subtle morphological differences, species are identified. The research showed that the species C. tibialis dominates in Austria as well as in Croatia. Not a single specimen of C. concinna was found in Croatia. The reason for the absence of the species C. concinna in the samples is not known, but further research could determine the factors that influenced the abundance of the studied species, given that it is known that sugar beet flea beetle populations are largely conditioned by environmental factors.