Abstract: This study was carried out to determine the effects of using formic and oxalic acids against Varroa jacobsoni Q. which is the most hazardous parasite of honey bees (Apis mellifera L.) alternately in different seasons on the efficiency in Varroa treatment and colony development of honey bees. About 35 honey bee colonies in same of queen ages (1 year old) from Buckfast race were used in the research. Colonies were equalized for natural varroa levels and adult-brood bee population, prior to the research. Colonies were selected randomly as 2 treatment groups with 14 colonies and one control group with 7 colonies in the autumn and then the treatment goups were divided into 2 for using organic acids alternately so, 5 research groups (O/F, O/O, F/F, F/O and control) were used for the following spring. Varroa levels, treatment effectiveness, adult bee and brood population growth of groups were determined in autumn and spring, before and after the research. In autumn and spring experiments, Varroa infestation levels of the treatment groups were significantly reduced after the oxalic and formic acid applications (p<0.05). After, the experiment in autumn, number of adult bee frames in the group treated with formic acid were found significantly lower than before the treatment (p<0.05). In this season, brood surface level in the group treated with oxalic acid were increased significantly (p<0.05) at the end of the spring experiment. The highest efficiency of organic acid (94.10%) were observed in the 1st group (O/F) but it was not found different from other groups (p>0.05).