Since 1986 perizin has been used in many European countries to combat the miteVarroa jacobsoni, a parasite of the honeybee. We have studied the long-term presence of coumaphos, the active ingredient of perizin, by analyzing honey and wax for residues. We distinguished between the direct transfer of coumaphos into wax by contamination during treatment and the indirect transfer through wax production by bees. To study the indirect transfer, we treated colonies with perizin and removed the combs, thus forcing the bees to produce new wax. The newly produced wax and honey were analyzed for the presence of coumaphos. Wax from colonies that had not been treated with perizin for 6 mo and up to 18 mo still contained coumaphos (7 and 1 μg/g wax, respectively). Moreover, newly produced wax from the colonies that had not been treated with perizin for 6 mo also contained coumaphos (≍17% of the amount found in old wax). No residues were found in honey. Only small amounts of coumaphos (±l‰ of the amount administered) were found in newly produced wax when colonies were fed a perizin-sugar solution. The largest amounts of contamination were found in the first samples secreted; samples taken 3-4 d after application contained only 1-5% of the amount secreted on the 1st d. Coumaphos is transferred mainly into the wax directly as a consequence of the application of perizin to combs, and the acaricide is persistent in the wax.