Background <p>The use of toxic sugar bait with ivermectin (TSB_Ivermec) has emerged as a promising strategy for controlling insects that feed on carbohydrates, particularly mosquito species, in areas endemic for arbovirus transmission. The aim of this study was to evaluate the effectiveness of TSB_Ivermec in controlling flies of medical and veterinary importance. We assessed the overall mortality of adults of two species, <i>Peckia</i> (<i>Sarcodexia</i>) <i>lambens</i> and <i>Chrysomya megacephala</i>, and the effect of different ivermectin concentrations on fly mortality.</p> Methods <p>Concentrations of 0.012%, 0.025%, and 0.050% ivermectin diluted in 20% sucrose were tested on groups of 40 adult flies (1:1 male:female), aged 4–8&#xa0;days. Exposure to TSB_Ivermec lasted for 6&#xa0;h, and mortality was monitored for up to 96 h and compared to that of a control group with no ivermectin exposure.</p> Results <p>Both species showed cumulative mortality of 100% at the highest concentration of ivermectin (0.050%), although <i>P.</i> (<i>S</i>.) <i>lambens</i> was more sensitive to the compound than <i>C. megacephala</i>, with most deaths occurring within the first 24&#xa0;h. At lower concentrations, mortality ranged from 97 to 81% for <i>P.</i> (<i>S</i>.) <i>lambens</i> (at 0.025% and 0.012%, respectively), and 78–57% for <i>C. megacephala</i>. Mortality differed significantly between these species (<i>P</i> &lt; 0.001), but not between the sexes (<i>P</i> = 0.8). TSB_Ivermec demonstrated high efficacy against both species under semi-field conditions.</p> Conclusions <p>The results suggest that the 0.050% concentration of ivermectin, which is known to be effective against mosquitoes, is also optimal for the rapid population control of synanthropic flies, enabling its integrated use in highly infested or vulnerable environments, such as health care facilities.</p> Graphical Abstract <p></p>