Multifactorial eco-friendly composition and procedure for treating varroosis in honeybee colonies using a rapid application system that does not require hive opening. The composition contains food-grade petroleum jelly, oxalic acid and thymol in varying proportions adapted to the requirements of differing climatic zones and stages of honeybee colony development. It is applied by spreading it with a toothed utensil on a semirigid bearer provided with a scale used to adjust the dose to the state of development of the hive and to the time of application. It is inserted into the hive via the entrance and is provided with a flange that remains outside the hive to facilitate handling. It is the bees themselves that, by walking on the composition, spread it throughout the hive, achieving 100% efficacy without permitting development of resistance to the treatment, as it attacks the parasite on multiple fronts It therefore represents a new paradigm in the battle against varroosis in honeybees.